The General Permitted Development Order Part - 1 Class A Q & A DCP Section 4.34

This section deals with the interpretation of the principal provisions of the Statutory Instrument entitled Town and Country Planning (General Permitted Development) Order 1995 - as amended. It also covers the equivalent legislation in Scotland and Wales, both under review at the time of writing. However, information and commentary on the GPDO will concentrate on the English Order, to which radical and controversial changes to Part 1 were made in 2008.

Q & A Part 1 Class A 4.34/102

For the purposes of Part 1 Class A 1(g) of the GPDO can you confirm that the erection of a building includes extensions to listed dwellinghouses or whether section (g) is referring solely to detached buildings within the curtilage of a listed building?

The definition of a "building" in the Order includes part of a building. Despite the confusing reference to "curtilage", this proviso is specifically included under the Class A heading relating to "the enlargement, improvement or other alteration of a dwellinghouse", and the exemption from PD rights stated at A.1(g) must refer thereto. In defence of the draftsman of the Order an extension to a house does technically fall within its curtilage. It is of note that Class E, relating to detached buildings within the curtilage of a listed building, does give a limited PD right within listed building curtilages of 10 cubic metres.

As a local authority we have a situation where at a dwellinghouse there is an existing 30 cubic metre single storey rear extension and planning permission for a two storey side extension of 175 cubic metres. The latter is unimplemented. It is now proposed to double the size of the existing rear extension, but this would only make 60 cubic metres, in itself still within the limits for permitted development relative to this property. Does the fact that that there is an extant permission for the side extension affect the position?

On the face of it Class A would seem to permit the combined extension of 60 cubic metres as the resulting building would be extended by less than 70 cubic metres compared with the original building.  The existence of the planning permission would make no difference since it does not impinge on a calculation based on the difference between the original and the resulting dwelling. However, if the two storey extension was built first it could be argued that this would then contribute to the resulting dwelling calculation. The counter argument to this would be that the whole purpose of the GPDO householder classes is give a freedom for a specified amount of extension to a dwellinghouse  which may be undertaken without planning permission. Therefore any development undertaken with planning permission should not be counted. Any reader views on this interesting point?

Response

In practice I have adopted the approach of obtaining planning permission for an extension, following this with a PD proposal to be built first. On completion advantage can then be taken of a valid planning permission. I suggest that it is right and proper than the PD rights given by Parliament were intended to be used this way. Incidentally, I read with pleasure, and support the editor's comment, with regard to the garage case reported in the same issue (page 18). All the councils I deal with adopt the deduction rule even if the garage were built with the house.

The key in all these cases is to carry out the PD work  before you commence the development that has planning consent in case the planners have, as they should have, removed PD rights when granting the consent.

You have touched on a tactic often used to maximise householder development. Knowing certain development may not be to the LPA's liking, planning permission is sought for that which is OK. The more sensitive development is then commenced as PD allowing for later implementation of the approved work.  Like many aspects of the GPDO loopholes are there and it then rests with the ingenuity of the LPA to bring under control that which they wish to control.

Having worked for various local authorities I am aware of the ambiguity of the situation. Personally, I believe this is a nonsense as it prejudices those who are fortunate enough to have a detached garage, and also creates difficulty in interpretation of what is "attached".

A dwellinghouse has a small, separate outside toilet building within its garden. This building is within 5 m of the house and built at the same time. Does this toilet comprise part of the original dwelling house for the purposes of assessing permitted development under Class A of the GPDO?

Cases have shown that detached buildings erected at the same time as a house, such a garages etc., should not be included in the calculation relating to the "original" dwellinghouse as defined in the GPDO.  Whether they should be brought into the calculation relating to the "resulting" building is another matter!

A cantilevered balcony has been created to the first floor of a two storey extension to a dwelling erected with planning permission. A new patio door access has been provided but railings or walls have yet been constructed around the balcony. It does not appear that these works transgress the permitted development rights given by the GPDO Part 1 unless one may argue that because the extension which has been altered exceeds the size limits in Class A, the alteration works fail to be permitted development. Have you any comments?

The original extension presumably needed planning permission because the cubic tolerance available to the dwelling was exceeded. It has been argued before in these columns as to whether extensions to dwellinghouses for which express planning permission has been granted should or should not be counted against the volume ceilings given for permitted development (PD). If we assume that they do, and there is no PD volume available, one needs to look at the question of whether such a balcony would have a volume to be measured. In terms of the slab itself this is unlikely as the GPDO refers to cubic content. Even if railings or walls had been erected there is no hard case evidence to suggest this would on its own have created a cubic volume for the purpose of the Order. The area under the balcony would similarly not be space that is sufficiently enclosed.  It would seem that the whole of these works including the patio doors would fall to be PD as "the enlargement, improvement or other alteration of a dwellinghouse", as none of the conditions in Class A would seem to be transgressed.

My colleagues and I are unsure whether planning permission is required for the creation of a light well abutting a house so that a window may be inserted to the basement?

I imagine that this is a dwellinghouse to which householder permitted development rights apply. Class A would seem to give a deemed permission to these works if they are anywhere but between the existing dwelling and the highway, in which case condition A.1(d) would apply.  If the cubic tolerance allowed by A.1(a) has been used up it may be debated as to whether the well itself has a cube to be measured, but the fact that there is no roof may count against such an assessment.

By virtue of Class A1(d) of Part 1 of the General Permitted Development Order 1995 development is not permitted at a dwellinghouse if the part of the building, enlarged, improved or altered would be within 2 metres of the boundary of the curtilage of the dwellinghouse and would exceed 4 metres in height. There are two camps in this office as to how to interpret this provision. One takes the stance that the whole of a such a proposed extension is caught by the proviso if any part of it is over 4 m. The other view is that the extension only requires express permission if that part within 2 metres of the boundary is over the 4 m height figure. We would be interested in your interpretation.

The editor of the Encyclopedia of Planning Law and Practice is of the opinion that it is the whole of a proposed extension that is caught by this provision, and trying to read the words used in the Order literally I would tend to favour that interpretation as well. However, the alternative view is quite arguable, especially if one considers that the intention of the A1(d) proviso must be solely to prevent overbearingly high buildings being erected close to property boundaries using permitted development rights. If extensions more than 4 m in height could be allowable as permitted development if their footprint does not trangress the 2 m mark, the question is begged as to why control is required if parts at a lower height do go beyond it.

The GPDO states that development on Article 1(5) land which includes conservation areas is not permitted if it consists of the cladding of any part of the exterior of a dwellinghouse with plastic. Does it then follow that UPVC windows in conservation areas require permission?

An ingenious construction, but I somehow doubt that the word "cladding" would be construed in this way if the matter were ever considered in the courts.  However, your question does point to an urgent need to bring replacement plastic windows at conservation area houses within planning control, rather than forcing local authorities to go down the Article 4 Direction route.

Following a grant of planning permission, an extension to an existing dwellinghouse within a large curtilage was built over 20 years ago. Contemplating further additions, does Class A1 of the General Permitted Development Order 1995 (GPDO) regard the original dwellinghouse as the structure as built or has the passage of time given this benefit to the extended building?

The Order defines "original dwellinghouse" as that existing on the appointed day or if constructed later "as so built". Therefore on the face of it any post 1948 addition, whether built with planning permission or not, would count against the cubic tolerance applicable.  As I have put before, this interpretation runs counter to a view that the householder provisions of the GPDO were intended to provide a ceiling for additions to a house which may be constructed without planning permission.  Be that as it may, one cannot argue with the wording of the law as it is.

Does an Article 4 Direction in a conservation area, affect the erection of a single storey extension at the rear of a terrace house when the site is only visible from adjoining gardens?

The minimum effect of a confirmed Article 4 Direction will be the removal of Part 1 permitted development rights. Therefore any rear extension will require express planning permission. On receipt of an application, it is a matter for a planning authority to consider whether harm would be caused to the character and appearance of the conservation area, and "visibility" will be part of this assessment.  On the evidence of appeal decisions the question of whether a "hidden" house extension would cause any harm has been considered several times, and examples may be quoted where the fact that a proposed structure would not be seen from a public vantage point has been conclusive.

Response

It cannot always be assumed that the minimum effect will be the removal of all Part 1 rights. An Article 4(1) direction requiring the confirmation of the Secretary of State could well include removal of all Part 1 rights. However, in the case of an Article 4(2) direction, which need not be confirmed by the Secretary of State, rights can only be removed for developments which front a highway, waterway or open space. In both cases details of the specific direction needs to be checked as the Government encourages selectivity in the withdrawal of rights to those which constitute a specific threat.

I am trying to establish whether the construction of brick skins around existing concrete panel dwellings needs planning permission. While the works are clearly development, Part 1 of the General Permitted Development Order 1995 (GPDO) allows improvements or alterations to dwellinghouses. However, the proviso at A1(d) excludes works within 2 m of a boundary where they exceed 4 m in height. What is your interpretation?

As you aver, the recladding of a dwellinghouse in this way is development as defined by section 55 of the Town and Country Planning Act 1990, but is generally permitted by Part 1 of the GPDO provided that the original walls remain.  However, a strict reading of A1(d) would suggest that cladding is indeed not permitted if it extends higher than 4 m and is within 2 m of the property boundary. While I cannot imagine it was the intent of the authors of the GPDO to control cladding in this way, the law must be interpreted literally.  Another provision of the GPDO which could come into play is A1(c) which refers to alterations bringing the dwellinghouse nearer to a public highway. However, in this case the cladding would have to extend further forward than any existing cills or other projections.

A terraced house, close to but outside a conservation area, has had UPVC cladding added to its front elevation. I am aware that in the court case City of Bradford v Secretary of State for the Environment 1977 it was held that cladding would not be permitted development by reason of being between the forwardmost part of the house and a highway so long as it remained behind projections such as cills.  However, in this case the permitted development cubic tolerance available to the house has been used up and I would like to argue that, as the UPVC cladding is affixed by battens or studs, there is an air gap which could be considered an additional small volume. As my authority is anxious to control this unattractive cladding I would be grateful for your comments.

I do not have reference to a case where cladding standing proud of a building has been held to enclose a volume adding to cubic content. However following the court judgment in London Borough of Richmond upon Thames v Secretary of State for the Environment and Neale [1991] , which concerned parapet walls around a flat roof, it is clear that developments held to enlarge a dwellinghouse do not necessarily need to provide usable space, and could be cosmetic.  My inclination is that in this case there is a volume to be calculated which might exceed what would be regarded as de minimis and therefore bring this cladding within planning control.

Looking at the other conditions set out in Schedule 2 Part 1 of the General Permitted Development Order 1995, I wonder whether it may also be worth considering the applicability of restriction A1(d) which does not allow enlargements, improvements or other alterations to a dwellinghouse within 2m of the curtilage boundary and which are over 4m in height.

Do you know of any cases that have addressed the issue of what constitutes a terrace house for the purpose of part 1 class A(a)(i) of the GPDO? In particular, would a link-detached house be a terrace house for the purpose of this section if it was for one of three or more such houses linked by attached garages.

This point is an issue as the cubic tolerance allowable is set at a lower figure if the dwelling is a terrace house. In the 1995 Order a terrace house was carefully defined as meaning a dwellinghouse situated in a row of three or more dwellinghouses used or designed for use as single dwellings  where a) it shares a party wall with, or has a main wall adjoining the main wall of the dwellinghouse on either side; or b) if it is at the end of a row, it shares a party wall with or has a main wall adjoining the main wall of a dwellinghouse which fulfils the requirements of a) above.  I would not have thought that houses linked by garages are terrace houses for the purpose of this definition given the use of the terms party wall or main wall, but do not have any case evidence for this view. Have any readers had experience of this problem?

I am seeking clarification of what would constitute an "original dwellinghouse" as set out in part 1 class A(1)(a) of the General Permitted Development Order 1995. My particular interpretation would be that a garage within 5 metres of a pre-1948 dwellinghouse and constructed at the same time would in no way impinge on permitted development rights. Please can I have your opinion regarding this point?

This question has arisen at appeal several times. For instance, in a 1995 decision made by the Secretary of State it was averred that an outbuilding erected in 1936 at the same time as a house and 1.5 metres away from it "cannot be regarded as part of the original dwellinghouse for the purpose of paragraph A(1)(a)". It was reasoned that the house and the outbuilding were two separate buildings within the dwellinghouse curtilage. However, as the outbuilding was within 5m of the house and remained on site, it was held that by virtue of paragraph A(3)(b)  the calculation relating to the "resulting building" should include its volume. There is commentary on these confusing provisions at (4.3446).

A householder obtains a Lawful Development Certificate (LDC) for the erection of a single storey extension to a house on the condition that a detached garage that would be brought within 5m of the house is demolished. The householder proceeds to build the extension but fails to demolish the garage, meaning that the extension requires planning permission as the cumulative content of the extension plus the garage exceeds 70 cubic metres. Does the extension then become permitted development if the garage is subsequently demolished?

As will be well known to regular readers of Forum considerable confusion is caused by the wording of the part 1 class A(3)(b) criterion contained in the General Permitted Development Order 1995. Assuming that the assessment in the LDC is correct, its terms would not be satisfied until the garage is demolished, but would come into effect as soon as this has taken place. Thus the present extension is unlawful and could be the subject of enforcement action, but would enjoy the protection of the LDC when the garage is demolished.

The General Permitted Development Order 1995 (GPDO) at part 1 class A.1(a) refers to the cubic content of the original dwellinghouse. When working out permitted development allowances is it correct to assume that the original dwellinghouse does not include a garage built at the same time and as part of the same planning approval, and therefore any such garage counts towards the permitted development allowances. There is a difference of opinion in my office and your clarification would be most appreciated.

A.1(a) is the proviso that development is not permitted if the cubic content of the resulting building would exceed the cubic content of the original dwellinghouse by varying prescribed volumes. The cubic content of garages or similar incidental ancillary buildings is normally included as part of the "original dwellinghouse" if attached or integral, but not if detached. For instance in a 1995 appeal case from Hillingdon concerning an extension to a terraced house having an existing outbuilding in its garden, the secretary of state averred that there were two separate buildings within the curtilage of a dwellinghouse notwithstanding the fact that they were built at the same time and shared services. In these circumstances he felt that the outbuilding could not regarded as part of the original dwellinghouse. However, in this particular case it was found that because the outbuilding was within 5m of the house it should form part of the resulting building for the purpose of the cubic content calculations using the controversial class A3(b) criterion, and should be taken off the 50cu.m tolerance available to the dwelling. Other decisions have seen class A3(b) interpreted as meaning that the cubic content of a detached outbuilding is only counted if a proposed extension acts to bring it within 5m of the dwellinghouse. I tend to favour the latter interpretation (see Planning 6 April 2001 pages 18 and 19). Whatever is the correct approach based on existing law, my personal opinion is that current permitted development rights should not be eroded as the result of the presence of buildings which predate planning control or have been erected with the benefit of planning permission.

I have always been led to believe that, providing all the conditions and limitations in the GPDO have been met, an air conditioning unit on a single family dwelling would be permitted development. My colleague has suggested that an air conditioning unit is not an extension, alteration or improvement to a dwellinghouse and should be treated as plant or machinery not benefiting from class A. Can you suggest who is correct?

Unfortunately, I cannot identify a case which directly assists in providing an answer to your query on the relationship of air conditioning units to part 1 class A of the GPDO. However I note that class A.(1)(f) refers to development not being permitted by this class if it is a satellite antenna. One inference from this is that such an exclusion would only be necessary if class A did not otherwise allow satellite dishes subject to all the other conditions within the class being satisfied. As a satellite dish is similar to an air conditioning unit in that it is service equipment bolted onto a dwelling, a parallel may be drawn. Of course, it must be considered whether an air conditioning unit is development at all by virtue of there being no material effect on external appearance. Such a ruling is quite possible, as in a 1991 secretary of state appeal decision from Totnes, south Devon.  The views of readers are invited on this interesting question.

What is the maximum permitted development volume for an outbuilding located within the curtilage of a dwelling in a conservation area? My interpretation is that class A.3(a)  of Part 1 of the General Permitted Development Order 1995 (GPDO) applies and that up to 50 cu.m is therefore permitted, However, other colleagues apply class E where the maximum permitted is 10 cubic metres.

As you state Class E does not allow any garden building of more than 10 cu.m on Article 1(5) land (which includes conservation areas). Looking at class A for more relaxed regulation, in A.3(a) the Order states that the erection of any building with a cubic content of greater than 10 cu.m shall be treated as an enlargement of the dwelling house for all purposes, including calculating cubic content, where the dwellinghouse is on article 5(1) land. On the face of it the Order is saying that if it is required to construct a garden building in a conservation area greater than the 10 cu.m limit allowed by class E, then that building shall be treated as an enlargement covered by class A and subject to the cubic tolerances therein. Your interpretation would therefore seem to be the correct one, and if not previously used up, a full 50 cu.m is available as permitted development in the circumstances described.

Response

There is clearly some logic in your interpretation, and this is the stance taken by the local authority where I am currently employed. However, my previous employer took an alternative view and this approach would seem to be endorsed by Circular 9/95 relating the 1995 consolidation of the GPDO.  At paragraph 43 it is clearly stated that class E excludes from permitted development the erection of buildings with a cubic content of more than 10 m2  anywhere within the curtilage of a dwellinghouse on article 1(5) land.

I note your point, which has also been made in similar terms by NW. However, I do not think that these words in the Circular take away from the general principle that works not permitted by the terms of one class may nevertheless be allowed by another. I do accept that it cannot have been the intention of the authors of the GPDO for class A to allow substantial outbuildings at dwellings in conservation areas, and it is hoped that the current review of the Order will clarify matters.

My planning authority in Scotland has received an appeal decision letter in which the reporter considered that timber decking measuring 10m2 and constructed against a detached dwellinghouse, fell within Class 3 (Part 1 Class E in England and Wales) of the Town and Country Planning (General Permitted Development) (Scotland) Order 1992. This would limit such decking to no more than 4m2 without the benefit of planning consent. I would have thought that timber decking could just as easily fall within Class 1 and could therefore be built up to 24m2 in area without the benefit of planning permission. What is your view?

There is certainly evidence from appeal decisions south of the border that decking physically adjoining a dwellinghouse, and which has a measurable volume, is a structure which may be considered to fall within Part 1 Class A of the GPDO (the equivalent of Part 1 Class 1 in Scotland). Reference should be made to the East Dorset case described and illustrated in (Planning 7 June 2000 p20).

Permission was granted for a side extension to a dwelling. The applicant now wishes to replace a conservatory, which in its own right would be permitted development under Part 1, Class A of the GPDO. However, does the fact that permission has been given for the extension, which takes the overall volume above 70 cubic metres, remove the rights for any other Class A additions, even if work has not yet started on the approved extension? Can a householder use up all their permitted development allowances and still build an approved development?

A similar matter was considered in R. (Watts) v SOS 2002. Mr Watts had permission for an extension but also wanted to build a roof extension at the same time under permitted development rights. The planning authority maintained that although the roof extension was in itself permitted development, when taken with the authorised extension it exceeded the GPDO tolerances and thus required express planning permission.

On appeal against an enforcement notice, an inspector concluded that all the works were being carried out as a single development, and since the combined cubic content exceeded the relevant allowance, the roof extension was not permitted by the GPDO. However, the court held that it was the timing of such building works that was important. Where development is carried out in accordance with the GPDO, its support is required until the works are substantially complete. But if before that happens the dwelling is otherwise enlarged, improved or altered so that the total cubic content of all the works exceeds the relevant allowance, the potentially permitted development would no longer be protected by the GPDO. In your case, therefore, it would follow that the conservatory could be built as permitted development before the extension, but not if built afterwards.

Response

Your advice on the timing of household permitted development rights raises a potential loophole. If permission is granted for a narrow extension 5m long and then ancillary living accommodation is erected within the garden at least 5m from the dwelling, under Class E permitted development rights, the two structures could be joined together. Could this be used to get round policies restricting the enlargement of Green Belt dwellings, or would outbuildings erected as permitted development invalidate the original permission?

While this is an interesting hypothesis, in reality there may be relatively few circumstances where permission would be granted for an extension of such a length since most planning authorities restrict extensions to about 3-4m, particularly in urban areas. Longer extensions would require careful assessment to ensure that their scale and appearance is satisfactory in relation to the host dwelling and that their impact on neighbouring living conditions is acceptable. As to whether the effect of any permitted development might be to render an extant permission invalid, I cannot conceive of any basis for this. However, where larger than average extensions are permitted it would be open to planning authorities to impose a condition removing Class E permitted development rights

The review commissioned recently by the ODPM recommends that where planning permission is granted for an extension, is extant and has yet to be built or completed, the permitted development rights of the property should be taken as having been used. This would mean that if the householder wanted a further curtilage building or extension, a planning application would be required and the planning authority could then consider if the two together would constitute over-development. That seems to me to be a sensible way to resolve this problem.

Further response

With regard to your advice that it would be open to planning authorities to impose a condition removing Class E permitted development rights, this is fundamentally flawed as the condition would only have effect after the permission had been implemented. In relation to the scenario described, to qualify as permitted development under Class E the development would have had to have been substantially completed before the development the subject of the planning permission was commenced.  In such a case, conditions attached to the subsequently implemented permission would not apply to Class E development which had already been carried out.

I accept that the second part of my reply was misleading but I had intended to make a more general point: that while permitted development rights cannot take away a planning permission, in certain circumstances a condition on the latter may be used to withdraw specified permitted development rights, such as those under Class E. But this would obviously not prevent the hypothetical situation posited, for the reasons you explain. However, the recommendation in the recent review of permitted development rights referred to in my advice would deal with this issue.

A householder wishes to build a two-storey rear extension that would be unacceptable in terms of Local Plan policy. The owner is arguing that the proposal would be permitted development on the basis that the volume of a substantial single storey building attached to the dwelling on 1 July 1948 but demolished soon after should be taken into account, since it formed part of the "original dwellinghouse" as described in the commentary to the GPDO 1995. Can the original dwellinghouse include something that has been demolished since the appointed day for the purposes of calculating cubic content?

Article 1(2) of the GPDO 1995 defines "original" as meaning "in relation to a building existing on 1 July 1948, as existing on that date and, in relation to a building built on or after 1 July 1948, as so built." While appeal cases lend support to the view that for the purposes of Class A, Part 1, Schedule 2 the volume of extensions which were previously present at a house but subsequently demolished may be offset against permitted development tolerances, the practical difficulty here may be in establishing the precise size of the original dwellinghouse.

My client owns a property in commercial use, between a residential street and a back lane, which has a hard surfaced unenclosed forecourt that has been used as a highway by pedestrians over many years. Permission was refused for a 1.5m high railing to enclose this space for garden use. However, I believe that my client has permitted development rights under Class A, Part 2, Schedule 2 to the GPDO 1995 to erect a railing under 1m in height to enclose the forecourt. But this would have the effect of changing the use of the land enclosed from highway to private use. What are the implications of this and is there any relevant case law? Would it require formal stopping up of the highway and, if so, under what legal provision would this best be achieved? GS

I cannot find a relevant precedent. However, I think the key issue is whether the forecourt is a highway for planning purposes. As the term ‘highway’ is not currently defined in planning law, decision-makers normally rely on common law usage which is that a highway is a way over which the public are entitled to pass and re-pass, including a footpath. Whether the public have established a right in law to pass over your client’s land is a matter on which you should take legal advice. If that right is proven, the effect of the boundary wall would obviously be to deny public access, requiring the stopping up or diversion of the highway. This might be achieved by an order under sec 247 of the 1990 Act, which enables a highway to be stopped-up or diverted to allow development to be carried out in accordance with a planning permission, including that granted by any development order. Alternatively, it might be possible to do this under the Highways Act 1980. You should therefore seek specialist advice from a highways consultant. Whether any change of use permission would also be required is arguable.

Response

Regarding the query about enclosing highway land, obviously before enclosing the land the owner would need to know whether it constituted public highway and, if it is, obtain the necessary closure order. However, if the land is not public highway, its mere enclosure would not, as the questioner suggests, constitute a change of use. Unless a new use is commenced, for example by adding the land to curtilage of an adjoining building, the site would have no use and just stopping a use does not require planning permission. Only where a new use is started would there be a material change of use.

My authority in south Wales deals with many cases where residents of housing estates built on steep slopes wish to level their gardens with decking or patios. Permitted development rights under Class F of the GPDO do not apply as hardstandings on flat ground are not created. I consider that whereas decking has a clearly measurable cubic content and should be assessed against Class A or E, the same cannot be said of patios because, as solid structures, they have no cubic content. This means that there are different rules for patios and decking, often with undesirable results. Am I correct in my interpretation and is there any chance that when the GPDO is revised decking will be excluded from Classes A and E, and fall within its own class?

Raised decking physically attached to and projecting from the rear wall of a dwelling and creating a measurable volume is a structure that may fall within Part 1 Class A.  In other cases, decking may fall to be assessed against Part 1 Class E. However, a solid patio cannot be considered against Class A as it does not enclose any measurable space, and where built on sloping sites the associated retaining walls will need permission as they do not have the function of a means of enclosure, as required by Part 2 Class A. Therefore your interpretation is correct.

Last year’s review of permitted development rights recommends that decking be excluded from a new Class A, dealing with development attached to the dwellinghouse, and fall within a new Class B, which covers development within the curtilage of a dwellinghouse.

I wish to extend my L-shaped house, which faces a curved public footpath, by filling in the recessed area and building in front of the forwardmost wall. Citing the limitation at Class A.1. (c) of the GPDO 1995, which deals with proximity to the highway, the planning authority has advised me that I need permission. However, the DTLR booklet ‘Planning - a guide for householders’ says that permission would only be required if I wanted to build closer to the highway than the nearest part of the original dwellinghouse to that highway which, because of the curved alignment of the footpath, I do not. In addition, the Encyclopaedia of Law explains that the limitation at A.1.(c) allows infilling up to a line parallel to the highway drawn from the closest point to it of the original dwellinghouse. As that line would not be breached, do I need permission? If not, how do I persuade the authority of this?

Although I am not aware that this type of situation has been considered before in relation to the application of A.1.(c), a literal reading of the limitation suggests that in this unusual case permission would not be required. However, I do not believe that those who drafted the Order envisaged that such circumstances would arise. Case law and ministerial appeal decisions relating to the interpretation of the wording used in the 1977 Order, which required that the extended building should not project beyond "the forwardmost part of any wall which fronts on a highway", have held that any development that would project in front of a parallel line following the line of the wall closest to and facing the highway, rather than from the particular point on that wall closest to and running parallel to the highway, would require permission. If the planning authority rejects your analysis but is likely grant permission in any event, the issue is clearly academic. But if is motivated by a desire to resist the proposal, you could consider applying for a lawful development certificate, seeking the authority’s confirmation that permission is not required, and then appeal against the probable refusal.

Can the demolition of part of an "original dwellinghouse", such as an attached garage or coal bunker, be offset against later enlargements when calculating their volume for the purposes of Class A, Part 1, Schedule 2 of the GPDO? Case law suggests that detached garages and outbuildings within 5m count towards the allowance, even if existing on 1 July 1948 or "as so built" afterwards, but does this also apply to an attached garage?

Although the courts have held that the rebuilding of a dwellinghouse in stages falls outside the scope of the Order, they do not appear to have addressed specifically whether the demolition of any part of a dwellinghouse can ever be offset against the tolerances under this class. This therefore continues to cause difficulties. However, in a case from Oxfordshire in 2001 an inspector held that a proposed extension was permitted development, even though it exceeded the relevant allowance, as it would be offset by the demolition of a garage forming part of the original dwellinghouse. A practical approach is often taken, subtracting the volume of the original dwelling from the extended dwelling, and discounting that which disappears as a consequence.

Although some inspectors have taken a contrary view, detached garages and outbuildings are not normally included in the calculation of the cubic content of the "original dwellinghouse", even when built before 1948 or contemporaneously with the house. But it is clear that an attached garage, built in similar circumstances, will form part of a dwellinghouse.

Response

Once a dwellinghouse has used up all its permitted development allowances express permission will be required for all further extensions. In this case, the demolition of an existing extension and its replacement by another of an equivalent volume would still result in a building with a cubic content exceeding that of the original dwellinghouse by more than 70 cubic metres. As this would breach the limitation at A.1 under class A, I consider that the planning authority’s approach to this matter is correct.

At what stage does a single dwellinghouse lose its permitted development rights when it is converted into flats, either with or without permission, and the developer is no longer able to rely on the GPDO 1995 if he wants to build an extension? Does it make any difference if a Certificate of Lawfulness has been granted for the extension?

I can find no definitive rulings on this matter or on the opposite scenario of a when new dwellinghouse acquires such permitted development rights. However, commonsense suggests that the developer would be able to extend the building in accordance with Class A, Part 1, Schedule 2 of the Order up until the point that the building is no longer recognisable as a single dwellinghouse or capable of being occupied as such, in accordance with the criteria set out at paragraph 2.81 of Circular 10/97. These include the physical condition of the building and whether it has been adapted for more than one self-contained unit of occupation. I assume that your reference to a certificate of lawfulness is in respect of the proposed extension of the existing single dwellinghouse. Clearly, that could not be relied upon to support a subsequent extension to the building once converted to flats.

Response

The answer has to start from an understanding of a planning permission for the erection of a dwellinghouse, which includes two steps. First, permission is granted for a building designed to be used as a dwellinghouse. Second, permission is given for that building to be used as a dwellinghouse. Until that use commences, that is to say it is dwelt in, it is not a dwellinghouse but is still only a building. Once it has been occupied for the approved purpose, the occupier can then enjoy the benefit of permitted development rights. In the case of the original question, the same basic principles apply. While the dwellinghouse is still occupied as such, permitted development rights apply as internal alterations do not constitute development. But as soon as it is occupied as flats, there are no such rights. It does not matter if planning permission has been granted, or not, since it is the use itself which is the determining factor.

In determining whether permission is required for garden decking, should any volume created underneath be considered an enlargement to the dwellinghouse under Class A, Part 1, Schedule 2, of the Town and Country Planning (General Permitted Development) Order 1995 or would it be de minimis? Would this depend on whether the decking is to be constructed on sloping ground, which would create a void between the posts needed to support the structure? RH

The approach taken by inspectors has been that decking is more than just a surface. Thus where physically attached to a dwelling and creating a "measurable" volume, decking is considered to be a building to be assessed against the limitations under Class A. The measurement of its cubic content will include both the volume of the structure itself and any space between it and the ground, if enclosed by the decking.

In 1957, about 30% of a large un-extended detached house that had been built in 1913 was demolished. Plans exist of both the original house and as subsequently reduced in 1957. My client has purchased the property and wishes to rebuild the demolished part and add his Class A, Part 1, Schedule 2 of the GPDO permitted development. The resulting dwelling would thus be 70 cubic metres larger than existing on the appointed day. Do you agree that this can be done without the need for express permission? PE

Paragraph A.1(a) provides that development is not permitted by Class A if as a result of the proposal the cubic content of the resulting building would exceed the cubic content of the original dwellinghouse by more than 70 cu m, in the case of a detached dwelling. "Original" is defined in Article 1(2) of the Order as meaning either the house as existing on 1 July 1948 or, if built after that date, as so built. "Resulting building" is defined in paragraph I of Part 1 as the dwellinghouse as enlarged, improved or altered, taking into account any enlargement, improvement or alteration to the original dwellinghouse, whether permitted by Part 1 or not. As the proposed works to rebuild and extend the property would not result in a dwellinghouse exceeding 70 cu m larger than that existing on the appointed day, I agree that express permission is not required. This view is supported by recent appeal decisions.

Based on guidance given in Development Control Practice, I recently advised that express permission was not required for replacement cladding to a semi-detached dwellinghouse that is not within a conservation area, or subject to an Article 4(2) Direction, or had its permitted development rights withdrawn by planning condition. However, I have since noticed the proviso at Class A (d) Part 1 Schedule 2 of the General Permitted Development Order (GPDO) 1995.  Bearing this in mind, would cladding at first floor level to a semi-detached or terraced house within 2m of the site boundary require permission, as it would be an alteration to a building over 4m in height?

Except where cladding would project forward of the part of the original dwelling nearest to the highway, which can include window sills and eaves, or involves a sensitive area such as Article 1(5) land, cladding will normally be permitted development. This follows the judgement in Bradford MDC v Secretary of State for the Environment [1977]. Here the court held that the fixing of stone cladding to the face of a dwellinghouse was development as it would materially affect the external appearance of the building and thus fell outside sec 55(2)(a) of the 1990 act. However, it was also determined that it was permitted development under Class I of Schedule 1 of the 1977 version of the GPDO.

The proviso at A.1 (d) of the current Order says that 'in the case of development other than the insertion, enlargement, improvement or other alteration of a window in an existing wall of a dwellinghouse, the part of the building enlarged, improved or altered would be within 2 metres of the boundary of the curtilage of the dwellinghouse and would exceed 4 metres in height'. This differs from the wording given in the 1977 version and, in my view, suggests that in this case permission would be required for the replacement cladding.

My authority is unclear over how Class A (d) to Part 1 of Schedule 2 of the GPDO should be interpreted. Officers have previously advised that providing that part of the structure or extension which is over 4m falls outside the 2m distance from the boundary, express permission is not required. However, an alternative interpretation based on a review of the Order and advice in the Encyclopaedia of Planning Law is that it if any part of the extension is over 4m and within 2m of the boundary, permission will be required irrespective of whether that part that exceeds 4m in height is outside the 2m distance from the boundary. Can you advise please?

There is no definitive guidance on the matter or discussion in last year’s ODPM commissioned review of permitted development rights. Both interpretations may be argued. A literal reading of class A.1 (d) appears to favour the view taken by the editor of the Encyclopaedia and this is supported by a case earlier this year from Bromley (DCS No: 36853264). However, if the intention of the proviso is to prevent overbearingly high buildings from being erected close to property boundaries under this class, the question must be asked why if extensions more than 4m in height are permissible under the Order where their footprint does not transgress the 2m mark, why should express permission be required if parts at a lower height go beyond it?

A condition of a permission for a small domestic rear extension requires approval of detailed drawings for the proposed traditional windows and doors before work starts on site. It also requires the scheme to be implemented in accordance with the approval. However, my client now wishes to install modern windows. Despite the condition, it has been suggested that these changes could be made under Class A.1 (d), Part 1, Schedule 2 of the GPDO 1995. Do you agree and would the originally approved windows need to be installed before they could be replaced?

Replacement windows do not normally need planning permission as they are permitted under this class. But any material change to the windows prior to substantial completion of the extension would be in breach of the condition, unless specifically authorised under the approval process resulting in its discharge. Nevertheless, while the apparent purpose of the condition is to secure the use of traditional windows, once the extension has been completed in accordance with the permission and approved details, if there is no condition requiring their subsequent retention or expressly removing permitted development rights, I think it would be lawful after a reasonable period of time to replace them with windows of a modern design.

Response

I am dealing with a similar situation in that a conservatory was erected prior to substantial completion of a new dwelling and therefore did not benefit from permitted development rights. One option is for the householder to remove the conservatory and its footings, infill the excavations, and then re-erect the building under permitted rights that now apply to the completed dwelling. What, therefore, would be a "reasonable length of time" between these two operations to indicate a clear distinction between a breach of planning control and the undertaking of permitted development works?

Further Response

I am not aware of any ruling on this. However, the elapse of time need only be sufficient to demonstrate that the conservatory was not built at the same time as the house but followed its completion. In my view, it would be extreme to remove the extension. The authority would clearly be at a disadvantage if it took enforcement action since the fall-back position created by the permitted development rights that the dwelling now enjoys would be a material consideration in favour of allowing any appeal. If the authority feels that it is necessary to intervene, it should request a retrospective application.

My client built a conservatory measuring about 30 cu.m. to the rear of his otherwise un-extended detached house on the advice of a supplier who advised permission was not required. The conservatory does not face a highway. The house was built 15 years ago with a detached garage within 5m of it, measuring more than 70 cu.m. The conservatory does not lie within 5m of the garage. Citing the 1991 Adur District Council ministerial appeal decision, the planning authority argues that permission is required due to Class A3(b), Part 1, Schedule 2 of the Town and Country Planning (General Permitted Development) Order 1995. However, the authority’s view conflicts with advice in the Planning Encyclopaedia, which reinforces my understanding that it is only where the extension would bring the dwellinghouse to within 5m of any existing building that Class A3(b) applies.  Other planning authorities take an inconsistent approach to this matter. Who is right?

Recently inspectors have reached a different conclusion from that of the minister in 1991. In the absence of any judicial authority on this matter, they have ruled that the interpretation of the Order should turn on the ordinary meaning of terms used in the legislation. In the case of criterion A.3, inspectors have held that the words "would be" in the context of class A as a whole indicate that the provision is intended to apply only where part of the dwelling previously more than 5m from any existing building in the curtilage would be brought within 5m of that building as a result of the proposed development. Support for this view is taken from the original wording of the 1977 Order and paragraph 40 of circular 9/95, which summarises the Order and explains how cubic content should be calculated where "a dwellinghouse is to be extended to within 5m of an existing building". This approach is consistent with the editorial comment in the Planning Encyclopaedia.

My authority is unsure whether a swimming pool house within 5m of a detached garage, which in turn is within 5m of the dwellinghouse, should be considered under Class E or Class A of Part 1, Schedule 2 of the General Permitted Development Order 1995. While case law indicates that a building within 5m of a dwelling would be considered under Class A as an enlargement to the dwelling, I cannot find any reference to a building that would be permitted by Class E, were it not for an intervening building. The answer seems to rest on the definition of a "dwellinghouse", as paragraph A.3 (b) of Class A refers to the situation where a building is within 5m of the dwellinghouse but this does not mention other buildings. The garage was not part of the "original" dwellinghouse. What is your view?

The effect of E.1 (c) is that where such a building would have a cubic content greater than 10 cu m and any part of it would be within 5m of any part of the dwellinghouse, it is not permitted. "Dwellinghouse" is not defined in this context, or qualified by reference to either the original dwellinghouse or one that has been enlarged under Class A. The difficulties with interpreting A.3 (b) have been debated repeatedly. However, I cannot see how this applies, since it relates to enlargements that would bring a dwellinghouse to within 5m of an existing outbuilding. But while the garage could be treated as an extension to the original dwellinghouse under Class A.3 (a) (ii), I do not think it was the intention of those who drafted the Order to treat curtilage buildings that fall within 5m of such a garage as an enlargement of the dwellinghouse.

Response

You are correct in saying that paragraph A.3(b) to Class A, Part 1, Schedule 2 of the General Permitted Development Order does not apply, although he can only speculate as to the drafters' intention regarding A.3(a). Without any such confirmation or court ruling, we surely have to consider what the Order says, rather than what we might think it meant to say. On that basis, if the proposed building would exceed 10 cu m in volume, it would fall under A.3(a)(ii), as A.3(a) requires that the garage shall be treated as an enlargement of the dwellinghouse and the proposed building would be within 5m of it.

A.3(2)(ii) seeks to limit the enlargement of a dwellinghouse by requiring that where there is a building with a cubic content greater than 10 cubic metres that would be within 5m of that dwellinghouse, the volume of that building shall be deducted from its permitted development allowance. The provision does not go beyond this to require that a building that exceeds such a volume that would be within 5m of another building, which itself exceeds such a volume and is within 5m of the dwellinghouse, should also be treated as an enlargement under this class. I therefore disagree with your interpretation.

A patio has been constructed next to a dwelling on a sloping site. It is 0.95m above ground level where it meets the rear wall of the house, but increases to a maximum of 1.3 m away from the house. The patio is 4.85m deep and has no railings. Permitted development rights have already been used up by previous extensions. Is the patio development requiring express permission and would the situation change if railings were installed?

A raised patio physically attached to and projecting from the rear wall of a dwelling which creates a measurable volume is a structure that falls to be judged against the limitations of Class A, Part 1, Schedule 2 of the General Permitted Development Order. As that seems likely in this case, express permission will be required. A raised patio that is detached from a dwelling should be assessed against Class E, while a patio at ground level may be permitted under Class F. In a recent case from Buckinghamshire (Planning 2 September, p18) an inspector held that the raising through the use of cement of an existing patio attached to a dwelling that was already 1.5m above ground level by a further 44 cm, could not amount to the provision of a hard surface to be judged against Class F. Instead, it was an additional enlargement of the dwelling (DCS No: 100038321). The installation of railings around the patio may create additional volume to count against permitted development allowances, but only in the thickness of the railings themselves.

Class A.1(g), Part 1, Schedule 2 of the General Permitted Development Order 1995 says that permission is required to enlarge a dwelling where "it would consist of or include the erection of a building within the curtilage of a listed building". Article 1 of the Order states that a "building" includes "any structure or erection" and with certain exceptions "includes any part of a building, as defined in this article". This implies that extensions may be classed as buildings and so any extension to a listed building needs planning permission as well as listed building consent. The latest version of Planning: A Guide for Householders explains that permission is required for extensions to listed buildings, whereas previous editions did not. So do all such extensions now require permission?.

As noted in 4.3421, for the reasons you give it may be fairly inferred that all extensions to listed dwellings have no Class A permitted development rights and will require express permission. However, since nearly all works carried out to a listed house would require separate listed building consent in any event, this is largely of academic interest. The inclusion of the phrase "within the curtilage" creates some difficulty, since this would normally refer to free-standing buildings. But as Class A only applies to works to a dwelling, there can be little doubt that it cannot refer to garden buildings as these are dealt with separately in Class E. In my view, the ODPM’s latest guidance is correct.

A local authority is threatening enforcement action against a garage built more than 5m from a house because it lies within 5m of an outbuilding which is itself within 5m of the dwelling and is therefore not permitted under Class E, Part 1, Schedule 2 of the General Permitted Development Order 1995. Citing paragraph A.3(b), the authority considers that since the volume of the outbuilding can be added to that of the dwelling for the purpose of enlargements under Class A the outbuilding is part of the dwelling for all purposes and the 5m rule applies. Is it right?

There is no precedent or guidance in Circular 9/95 to support this approach. Paragraph A.3(b) applies where a proposed house extension would be brought to within 5m of an outbuilding, in which case the volume of that outbuilding shall be treated as forming part of the resulting building for the purposes of calculating cubic content under Class A. This paragraph is also relevant when considering the term "resulting building" under Class B, in accordance with the definition given in paragraph I. But that is not the same, in my opinion, as saying that the outbuilding forms part of the dwelling for the purposes of paragraph E.1(c), since paragraph A.3(b) does not apply to Class E and the term "resulting building" is not used. Paragraph E.1(c) does not set a limitation by reference to proximity to another outbuilding within 5m of the dwelling. Instead, the requirement is simply that any outbuilding larger than 10m3 should be no nearer than 5m to the dwelling and comply with other restrictions on height, location and site coverage.

The developer of a housing scheme wishes to provide an additional refuse storage facility enclosed by a 2m high fence on an area of incidental landscaping next to a public highway. Objectors argue that permission is required for both the fence and for change of use of the land. I have always understood that for the purposes of Class A, Part 2, Schedule 2 of the General Permitted Development Order (GPDO) 1995, land is no longer "adjacent to a highway" when it is at least 2m away from the road. I also consider that there would be no material change of use because there is no condition requiring the land to be retained as part of the landscaped area and the proposal would have no harmful impact. Am I right?

There is no rule of thumb on how far away a fence needs to be from the highway for it to not to be considered "adjacent". This is a matter of fact and degree and has been the subject of a variety of appeals. In a case from Buckinghamshire in 2001 (DCS No: 37201660), an inspector supported enforcement action against a wall about 2m from the edge of the carriageway on the grounds that this was sufficient for it to be considered adjacent. In a case from Oxfordshire in 1999 (DCS No: 34715308), which involved a countryside location with houses standing in reasonably spacious plots, the inspector judged that 6m was not a significant distance and the scheme amounted to development adjacent to a highway. If the proposed bin store is small in scale it should be considered ancillary to the overall primary use of the land for housing purposes.

A pair of semi-detached dwellings, one of which is listed, is prominently sited in a conservation area, next to two public roads. The unlisted house was rendered some time ago, presumably before its neighbour was listed. An Article 4 direction withdraws certain permitted development rights. The owner of the unlisted house wishes to remove the render to expose the original flint work, which could enable the building to be listed. Would these works be affected by the Article 4 direction and require permission?

Despite improving the dwelling, since the removal of the render is a building operation that would materially affect its external appearance, it would constitute development for the purposes of planning control. Class A, Part 1, Schedule 2 of the General Permitted Development Order 1995 grants permission for improvements and other alterations to a dwelling, subject to certain limitations. However, if the Article 4 direction expressly withdraws Class A rights, rather than proscribing specified developments, the works would require permission.

In considering an application to open up a major new window in the flank wall of a house, loss of privacy and quiet enjoyment of an adjacent property are among the relevant considerations. However, this issue does not arise with an application for listed building consent. So should an application to insert a window in a listed building be made under both sets of legislation? If not, which one takes precedence?

The window would only require planning permission if it would materially affect the external appearance of the house, and so constitute development, and rights to alter the dwellinghouse under Class A, Part 1, Schedule 2 of the General Permitted Development Order (GPDO) 1995 have been removed by a planning condition or Article 4 direction. Only in those circumstances would it be possible to take into account the effect of the window on neighbouring living conditions. But regardless of whether permission is necessary, listed building consent would be required, since it would almost certainly affect the character of a building of special architectural or historic interest. Listed building control is limited to ensuring that the building's special qualities are not harmed.

Condition (g) to Class A, Part 1, Schedule 2 of the GPDO provides that the enlargement, improvement or other alteration of a dwellinghouse is not permitted development if "it would consist of or include the erection of a building within the curtilage of a listed building". Does this condition just relate to detached curtilage buildings or does it also have the effect of taking away all or part of Class A rights for the extension or alteration of dwellinghouses that are listed buildings?

While the matter is arguable, Class A is generally interpreted as meaning that listed dwellings enjoy exactly the same permitted development rights under this class as unlisted dwellings except for development within the curtilage of a listed building, which is specifically excluded by condition A.1(g). But given the parallel requirement for listed building consent, this is largely academic.

I am involved in pre-application correspondence on a rear conservatory to a house that backs onto a footpath. The agent claims that permission is not required because there is a 3m wide grassed area between the garden and the footpath. What is your advice?

Class A, Part 1, Schedule 2 of the GPDO grants permission for the enlargement of a dwellinghouse subject to certain restrictions on size and proximity to a highway. If the footpath is a public right of way, it would be considered a "highway". Condition A.1(c) says that permission is not granted if the part of the building enlarged, improved or altered would be nearer to any highway "which bounds" the curtilage of the dwellinghouse than the part of the original nearest to the highway or any point 20m from it, whichever is nearer to the highway. While the words "which bounds" have not been clarified by the courts, they imply that the highway has to border the residential curtilage, in the sense that it must adjoin. They must be distinguished from the expression "fronts" on a highway, which appeared in a previous version of Class A and remains in Class B. The Order gives no guidance on which part of a highway the 20m distance should be measured from, although in Part 6 the operation of the "25m rule" is stated to relate to the metalled part of any road. In a decision from Hertfordshire in 2001 (DCS No: 75444426), an inspector held that a grassed amenity area around 20m deep adjoining a road could be regarded as part of the highway.

Following consultation with officers from other councils and with various practice manuals, my authority has found differing interpretations of Class A(d), Part 1, Schedule 2, of the GPDO. One view is that permission is required if the part of the extension that exceeds 4m in height is within 2m of the site boundary. The alternative view is that if the extension exceeds 4m in height and any part of it is within 2m of the boundary, but not necessarily that part over 4m high, then permission would be required. What is your view?

Condition A.1(d) says permission is not granted for development other than the insertion, enlargement, improvement or other alteration of a window in an existing wall of a dwelling where "the part of the building enlarged, improved or altered would be within 2m of the boundary of the curtilage of the dwellinghouse and would exceed 4m in height". Despite several revisions since it appeared in the 1977 version of the Order, this condition continues to cause difficulties for practitioners. The editor of the Encyclopaedia of Planning Law takes the view that it is the whole of a proposed extension that is caught by this provision and this is generally reflected in practice. Reading the words used in the GPDO literally, I agree with this interpretation, which is supported by an appeal decision from Kent in 2004 (DCS No: 36853264). However, the alternative view is also arguable, especially if one considers that the intention of the A.1(d) proviso must be solely to prevent overbearingly high buildings being constructed close to property boundaries using permitted development rights. If extensions more than 4m in height could be allowable as permitted development where their footprint does not transgress the 2m distance, the question must be asked as to why express permission is required if parts at a lower height step over this mark. Although the 2003 review of permitted development rights carried out by consultants suggested that the condition at A.1(d) should be amended, the Government decided that the report's recommendations were unduly restrictive. Instead, its latest householder development consents review steering group has recommended a shift away from the volume-based approach to one based on impact.

Can you clarify whether a detached garage constructed at the same time as a dwelling and within 5m of it would count towards the 50m3 and 70m3 tolerances allowed under the General Permitted Development Order (GPDO) 1995? Some authorities take the view it does not, whereas mine does. TG.

Class A, part 1, schedule 2 of the GPDO incorporates the qualification that "where any part of the dwellinghouse would be within 5m of an existing building within the same curtilage, that building shall be treated as forming part of the resulting building for the purpose of calculating the cubic content". This is not very clearly expressed, so it is not surprising that there is confusion about the interpretation of this class or that this query regularly crops up in Forum.
The issue is discussed in Development Control Practice 4.3446. The normal interpretation given to the phrase quoted above is that when an extension brings an outbuilding within 5m of the resultant house, whereas previously it was at least 5m away, then the volume of that outbuilding should be included in the volume calculations. Let us hope that this provision is made clearer when the GPDO is revised. JH.

I recently asked a planning authority whether permission is required to extend an already extended dwelling, built in the 1950s with a detached garage 1m from the dwelling. The proposed extension and the previous extension will be less than 70 cubic metres in total. However, the authority argues that the garage must count towards the permitted development total even though it is part of the original development. I disagree, as it is likely that permission would have been granted to build the house and the garage and therefore the permitted development rights should not be affected. Please can you advise?

Although this question has arisen several times before, the answer remains unclear. However, detached garages are not normally included in the calculation of the "original dwellinghouse", even when erected at the same time, and this approach has been supported by various appeal decisions. These include one by the Secretary of State in 1995, when it was held that an outbuilding erected at the same time as a house and 1.5m away from it "cannot be regarded as part of the original dwellinghouse for the purpose of paragraph A(1)(a)". While apparently unfair in my view, that would mean that the garage you mention will count towards the relevant permitted development allowance.

Response

Regarding the query about how detached garages should be treated for the purposes of calculating cubic content for permitted development purposes (Planning 4 June, p21), surely this matter is put beyond all doubt by Schedule 2 Part 1 Class A3 of the GPDO 1995? This indicates that "the erection within the curtilage of a dwellinghouse of any building with a cubic content greater than 10 cubic metres shall be treated as the enlargement of the dwellinghouse for all purposes (including calculating cubic content) where ... any part of that building would be within 5 metres of any part of the dwellinghouse; where any part of the dwelling house would be within 5 metres of an existing building within the same curtilage, that building shall be treated as forming part of the resulting building for the purposes of calculating the cubic content".

The A3(b) criterion to which you refer has caused difficulties of interpretation, particularly with regard to whether it applies to buildings erected at the same as the original dwellinghouse. The ministerial decision referred to in my reply ruled that it did. However, this was later contradicted in two appeal decisions where inspectors held that the criterion was not applicable as that would give rise to an immediate and significant reduction of Part 1 permitted development rights, and that could not have been the intention of those who drafted the Order. If it had, the word "is" would have been used in A3(b), rather than the phrase "would be". There is clearly an urgent need for clarification of this criterion.

I am investigating a complaint about a pergola that has been built in the garden of an unlisted terraced house which, for the purposes of the General Permitted Development Order 1995, is outside any designated area. The property has no existing extensions or outbuildings and its permitted development rights have not been removed. The pergola lies within 5m of the house and is more than 10m3 in volume. Opinion among my colleagues is divided on whether the structure should be treated as an enlargement of the house under class A, part 1, schedule 2 of the Order or as a curtilage building under class E. What is your advice? JP.

Although pergolas have open sides and roofs, such structures are normally considered to enclose space and be "building operations". However, many benefit from class E exemptions. In a case from Merseyside in 2002 (DCS Number 46799223), an inspector concluded that since a pergola enclosed a volume in excess of 10m3 and lay partly within 5m of a dwellinghouse, it did not fall within class E. Bearing in mind paragraph A.3(a)(ii) to class A, it appears that the pergola ought to be assessed as an extension to the house and may therefore be permitted development. PM.

A balcony has been constructed on top of a single-storey house extension, which it overhangs on three sides by 1m. It is surrounded by a balustrade and supported by posts. Can the space between the posts under the overhang be included in the volume calculation for permitted development purposes? Similarly, can the space between the floor of the balcony and the top of the balustrade also be included? GD.

For a structure to have a volume to count against permitted development allowances, it must have the effect of enclosing space. Given the general approach to open-sided developments such as car ports and pergolas, the degree of enclosure beneath the balcony appears likely to be sufficient for the resulting volume to be assessed under class A, part 1, schedule 2 of the General Permitted Development Order 1995. However, in London Borough of Richmond-upon-Thames v Secretary of State for the Environment and Neale [1991] the court held that a parapet wall around the roof of a first-floor extension did not add any volume to the house beyond that contained in the wall. As a material alteration to the shape of the dwellinghouse, it fell to be judged against class B. A similar approach might be taken in your case. PM.

Paragraph A.1(a) of class A, part 1, schedule 2 of the General Permitted Development Order 1995 grants permission for the enlargement, improvement or other alteration of a dwellinghouse provided the resulting building would not exceed the original dwellinghouse by a specified amount. If a house has already exceeded its permitted development allowance, does this prevent all further development even where no new volume is created, such as a new window? There has been much debate in my office on this issue. RC.

Paragraph I of part 1 explains that "resulting building" means "the dwellinghouse as enlarged, improved or altered, taking into account any enlargement, improvement or alteration to the original dwellinghouse, whether permitted by this part or not". However, if the development under consideration does not have the effect of enclosing space and creating a measurable volume it is hard to see how the resulting building would exceed the specified allowances, regardless of whether the original dwelling has already been extended in accordance with the planning permission granted by the Order or an express permission. It cannot have been the intention of those who drafted the Order that an additional window or other alteration should be proscribed in the circumstances you mention, assuming that the window is deemed to have a material effect on the external appearance of the building and thus constitute development in the first place. The fact that conditions are often imposed on permissions for extensions taking away rights to insert additional windows, such as that found at model 52 in annex A of Circular 11/95, supports the view that permitted development rights for alterations continue to be available after the volumetric allowances have been used up. PM.

Response

I have always believed that householders can improve or carry out other alterations to dwellinghouses under class A, part 1, schedule 2 of the General Permitted Development Order (GPDO) 1995, even when it is generally thought that householders are materially altering the appearance of their homes, because I can see no qualification in the Order that seeks to restrain them. Surely if those who drafted the Order had intended to curb the enthusiasm of home improvers then they would have made reference to the definition of development in the Town and Country Planning Act 1990? As an example of a common alteration that materially affects the appearance of a dwelling, one thinks of an unlisted 19th century house in an unspoilt terrace outside a conservation area where an owner widens his front window opening and installs a modern window type in place of a vertically sliding sash. Does this represent development and do authorities ask householders to apply retrospectively in these circumstances? Please explain how you have reached your view on this issue. JS.

Further Response

The authority I joined recently believes that even after an express permission to enlarge an unextended dwelling has been implemented, the house still benefits from full permitted development rights unless these are specifically removed by a condition of that permission. I think that this is a nonsensical approach because class A of the GPDO is quite clear in referring to the "resulting building" and the "original dwellinghouse". The authority also believes that an outbuilding with a mono-pitched roof of up to 4m in height can be erected under class E of the Order and claims that inspectors who have rejected this issue have got it wrong. What is your opinion? AB.

Further Response

JS appears to have misunderstood my advice. In accordance with section 55(2) of the 1990 Act, the insertion or widening of a window opening to a dwelling or other alteration will only constitute development where it would materially affect the external appearance of the building. But even where it is held to have such an effect, it will benefit from the permission granted under class A unless this is withdrawn by a planning condition or Article 4 direction. So permission would not be required in the example given by JS. This is consistent with my advice to RC.The approach taken by AB's authority is clearly flawed because it disregards the definition of "resulting building" in the Order. I am not aware that the courts have considered the issue of what constitutes a ridged roof for the purposes of class E. In such circumstances, inspectors have tended to rely on the dictionary definition of the word "ridge" and have thus held that two opposite slopes must meet at the top of a roof to create such a feature. A recent example is from west London in 2005 (DCS Number 100-039-198). However, some have argued that the fact that one of the sides of the roof is at a slope of 90 degrees does not conflict with the generally accepted definition. PM.

My client has a semi-detached house with a detached garage that was built at the same time. Five years ago he built an extension projecting to within about 3m of the garage. A lawful development certificate to confirm that a dormer extension is permitted development has been refused on the grounds that the volume of the original garage must now be taken into account in calculating the relevant allowance, by virtue of paragraph A3(b), part 1, schedule 2 of the General Permitted Development Order 1995. Is the authority's approach correct? RB.

This provision continues to cause difficulties and inconsistencies in approach, even among inspectors. Paragraph B.1(d) provides that the volume of the "resulting building" following a roof enlargement should not exceed the volume of the original dwellinghouse by more than a specified amount. "Resulting building" is defined under the interpretation of part 1 at paragraph I as meaning the dwellinghouse as enlarged, improved or altered, "taking into account any enlargement, improvement or alteration to the original dwellinghouse", whether permitted by this part or not. So it is necessary to consider whether there has already been any enlargement to the original dwellinghouse under class A and, in accordance with paragraph A.3(b), whether that has brought it to within 5m of any existing curtilage building. However, inspectors' recent practice has been that, where any garage within 5m of a dwellinghouse was built either before 1 July 1948 or at the same time as the original dwellinghouse, it will not be included in the "resulting building". So the authority's approach in this case appears to be wrong. PM.

My authority is considering an application for a lawful development certificate to confirm the extent to which a house can be enlarged without express permission. The applicants have added the relevant allowance under class A, part 1, schedule 2 of the General Permitted Development Order 1995 to the volume of the original dwellinghouse. Evidence has been submitted showing the size of the original house in 1948, part of which was later demolished. The planning officer argues that this resulted in a new, smaller dwelling to which the tolerances must now be applied. My view is that this is wrong and that any later demolitions are immaterial. Am I right? AS.

The courts have not specifically addressed whether the demolition of any part of a dwellinghouse can be offset against the tolerances under this class. However, the Order takes the "original dwelling" as the starting point, with "original" defined in Article 1 as meaning "in relation to a building existing on 1 July 1948, as existing on that date and, in relation to a building built on or after 1 July 1948, as so built". So if the building as enlarged does not exceed the relevant volumetric allowance when compared to that of the "original dwellinghouse", rather than that as subsequently modified, it is difficult to sustain an argument that permitted development rights do not apply. In a case from Oxfordshire in 2001, an inspector held that a proposed extension was permitted development, even though it exceeded the relevant allowance, because it would be offset by the demolition of a garage forming part of the original dwellinghouse. A similar approach was taken in a decision from London in 2003 (DCS Number 30842374).

Under Class A, Part (i), (iv) of the amended General Permitted Development order, development is not permitted if it involves: "an alteration to any part of the roof of the dwellinghouse." It would appear that if you were to construct a two-storey extension at the rear of the premises it would not be possible to interlock it with the existing roof as this would involve an alteration to the roof. Is this another error in the writing of this document or is my interpretation incorrect? AM.

The provisions are not clearly drafted, but I presume the intention is that a pitched roof on a new two-storey extension is classed as a new roof rather than a roof alteration. Without this presumption, the provisions relating to two-storey extensions would be negated. JH.

I would welcome an opinion of the meaning of "rear wall of the original dwelling house" - Part 1, Class A.1 (e) of the recent General Permitted Development Order Amendment for a traditional L-shaped Victorian house. Some authorities consider this as the rearmost original wall. Others apply the length restriction of Class A.1 (e) to both the main rear wall and the rear wall of the back addition. In doing this they are treating both as rear walls. Which is correct? JW.

I wish I knew. Either interpretation is possible. Until case law decides, I would favour the latter interpretation. It is unfortunate the legislation is not clear on this as the country has a large stock of such houses. JH.

Response

Should differences be drawn from the use of the words 'a' and 'the' in the recent General Permitted Development Order Amendment, i.e. In the respect of Class A for example would it be appropriate to interpret reference to 'a' being any, as in "a (any) side elevation" and 'the' being singular as in "the principal elevation" meaning a single principle elevation [the front] and "the rear wall" meaning the rearmost wall in cases where the rear elevation has a staggered rear walls? RF.


Further Response

As with ordinary speech, the use of the definite or indefinite article in legislation helps determine what is meant. The term "the principal elevation" does suggest there should be only one, though on some houses it might be difficult to determine which it is. When a house is "L" shaped at the rear, however, the use of the definite article does not greatly assist interpretation as it could be one of two and the Order does not say it should be the rearmost. JH.

Further Response

JH suggests the rear wall as referred to in the new General Permitted Development Order Part 1 "could be one of two".  I consider the rear wall is a single wall, which in the case of a staggered rear elevation might well be Z-shaped.  I have already been obliged to submit an appeal to obtain an independent view on this matter, where the council’s interpretation meant the new rules allowed a much smaller rear extension than was permitted under the old rules. AR.

Further Response

I am now aware of five suggested interpretations on this issue! It is a shame the law was not clearly drafted so we do not need test cases. Obviously we would be most interested to hear the outcome of your appeal. JH.

Permission has been granted for an extension that exceeds the 70 m3 volume limit for a house extension under Schedule 2 Part 1 Class A of the Town and Country (General Permitted Development) Order 1995 as it applies in Wales. This extension has not been built, but within the five-year commencement deadline, the householder has asked whether permission would be required for a conservatory just below the 70 m3 limit. Can the authority prevent the applicant building the conservatory then the previously approved extension? JL.

This is a loophole which existed in England pre-October 2008 as the same wording applied in both countries until then. It was possible effectively to circumvent the size restrictions in this manner. One way to avoid it is to impose conditions on planning permissions for domestic extensions preventing the construction of the extension if permitted development extensions are built first. If this is not done, the only possible course of action subsequently is an Article 4 Direction. JH.

My Authority is having difficulty assessing whether permission is required for aircon units on dwellings. There are not any provisions within the General Permitted Development Order 1995 as amended (GPDO) and we have therefore been assessing the ‘material affect’ of the works/units. In one case we have previously advised 3 units would not require planning permission but now a fourth has been installed. Advice on how to assess whether permission is required would be appreciated, as well as if you consider there to be provisions within the GPDO, with particular reference to article 1(5) land? PH.

As you recognise your first assessment should be whether the proposal represents development, i.e. does it materially alter the external appearance of the building? If it does, you would then have to assess whether the proposal was permitted development - classes A or B of part 1 of schedule 2 of the GPDO will normally be relevant. In the case where a fourth unit has been added, you can only assess these issues in relation to that fourth unit. Except for volume calculation purposes for class B, no account should be taken of the previous units. The only differences for Article 1(5) land would be in relation to the variations in permitted development rights, e.g. Class B rights would not apply. JH.

A conservation area boundary bisects a dwelling curtilage. The owner wishes to extend the house.  The dwelling and the area where the extension is intended are not in the conservation area. With regards to part 1, class A of the General Permitted Development Order 1995, as amended last October, should extensions to this dwelling be restricted by A.2? JR.

The restrictions in A.2 relate to "a dwellinghouse on article 1(5) land" and article 1(5) land, of course, includes a conservation area. Although part of the curtilage is article 1(5) land, the dwelling itself is not on such land, so I would not consider the additional restrictions would apply. JH.

Does the restriction on side extensions under A.2 of Part 1, Class A of the General Permitted Development Order 1995 (GPDO) as amended last year, which covers Article 1(5) land, relate to basement extensions that would project beyond the footprint, i.e. beyond the existing side elevation, albeit with the 'side extension' all underground? CW.

Last November the Department of Communities and Local Government published consultant’s proposals for new permitted development rights for domestic basements. See http://www.communities.gov.uk/publications/planningandbuilding/basementextensions. This commented, "Whilst there is a case that the silence of the GPDO implies that all basement extensions require planning permission, the overwhelming majority of local authorities interpret Part 1 of the GPDO to include underground extensions." Applying the amendment order provisions to basement extensions does raise certain interpretation problems, e.g. how one measures height. Regarding your specific query, assuming basements can be permitted development, the wording of the Order does mean a basement extension in a conservation area, etc projecting beyond a house side wall would require planning permission even though it might not be visible. In most such cases, however, obtaining planning permission should not be problematic. JH. 

Response

This document is a slightly modified version of the White Young Green report to the Householder Development Consents Review on Basement Extensions published in July 2007. It refers to the 2007 permitted development rules and has not been updated to take account of the revisions that came into effect in October 2008.  Thus, the reference to part 1 of the General Permitted Development Order quoted relates to the old rules and I agree most local authorities interpreted these to basements up to the volume limits. However the new rules do not refer to volumes and in my view until there is an Order that relates to basements, these are no longer permitted development. AR.

Further Response

It appears the government is looking at introducing specific permitted development rights for dwellings and this should clarify this issue. It does seem sensible to introduce a permitted development right for basements to dwellings and arguably other building categories. JH.

Class A of Part 1 of Schedule of the General Permitted Development Order 1995 as amended provides different limits for the projection of rear extensions on detached houses and semi-detached and terraced ones. Would linked detached houses, namely ones appearing detached, but joined only by say a garage at ground floor be classed as terraced houses? AN.

Whilst there is a definition of a terraced house in the Order, there is not one for a semi-detached or detached house. Thus, it would be appropriate to take the normal meaning of the word and a house was only linked to its neighbour by a garage would normally be considered to be detached. Furthermore, a terraced house is defined as one which shares a party wall with, or has a main wall adjoining the main wall of the dwellinghouse on either side (or is an end-of-terrace house) and linked houses would not seem to fit that description. JH. 

An extension on the rear of a property on article 1(5) land would be permitted development under Class A, Part 1, Schedule 2 of the General Permitted Development Order 1995 (as amended).  Through internal configuration is it then possible for the principal elevation of the dwelling to be changed so that the rear elevation of the extension would become the principle elevation of the dwelling?  This would potentially enable further additions to the property and outbuildings to be permitted development. The property I have in mind is set within an irregularly shaped plot and the principle elevation does not front the highway. LH.

The October 2008 amendment refers to the principal elevation of the original dwelling, so the scenario you envisage could not occur. This is confirmed by a recent appeal decision in Worcestershire (DCS no 100-065-307) which related to a class E outbuilding rather than an extension but the inspector nevertheless applied this principle.  JH.

The interpretation of the "new" permitted development rights in Schedule 2, Part 1, Class A.1(d) of the General Permitted Development Order 1995 as amended is causing some contention. If someone develops across from the front of a front bay window and they do not build forward of this, will it be permitted development? BL.

It would seem that, unlike with the previous provisions, this would require permission. The relevant provision refers to extending beyond a wall which fronts a highway and the extension you describe would do this. Furthermore, the guidance on interpreting these provisions on the Planning Portal website provides for a staggered rear elevation on an L-shaped house, so presumably this would also apply to a principal elevation. Two certificate of lawful development application appeal decisions in Essex and London (DCS Nos 100-065-481 and 100-065-520) support this interpretation.

Response

In 5 February’s Planning there was a query about front extension and JH referred to the Planning Portal for guidance on rear staggered extensions.  I have been unable to find that but have a case where the original house has a staggered rear elevation.  Straightforward reading of the October 2008 General Permitted Development Order Amendment suggests that the 3m is from the rear wall i.e. the furthest wall to the rear which could give a greater depth against another wall.  I suspect that the convenient interpretation would be 3m from any rear wall giving a staggered extension.  Are there any appeal cases throwing light on this or do we take the actual wording or the conservative interpretation? NB

Further Response

The advice can be found on www.planningportal.gov.uk There have been several appeals supporting your interpretation regarding houses with a staggered rear elevation, i.e. L-shaped, houses, e.g. DCS no: 100-065-383. I am only aware of one where an opposite interpretation has been given, DCS no: 100-065-398 and in this decision the inspector does not refer to the "Portal" guidance, so there is no indication why he did not follow it. JH.

I am trying to get an interpretation of class A.1(g) of part 1 of the October 2008 General Permitted Development Order amendment with respect to eaves on single-storey lean-to rear extensions.  As there are no eaves on the side elevation I wondering whether the only height restriction would be the overall four metre limitation. DW.

Eaves are defined as the overhang of the roof and as the lower side of the roof has these, provided the extension comes within 2 metres of the boundary, these should not exceed 3 metres height. The only other constraint would be the 4-metre limitation in class A.1(e). The only appeals I have seen on this issue confirm this interpretation, DCS numbers 100-063-729 and 100-065-440. JH.

A house has been completely clad in a white opaque marbled stone which gives it the appearance of what could be best described as "crazy paving". This is not of a similar appearance to the external materials used for the existing house so seems to need planning permission. Do you agree? SD.

Yes. I assume the house is not on article 1(5) land, i.e. not in a conservation area, national park or similar designation. Condition (A.3(a)) of class A in the October 2008 amendment to the General Permitted Development Order 1995 stipulates that, apart from for conservatories, external finishes for alterations to dwellings should be of a similar appearance to those used on the existing dwellinghouse and this is clearly breached. If it is on article 1(5) land, the prohibition of cladding in A.2(a) would apply. JH.

Response

Our team disagrees with JH and believes this would be permitted development. Class A of part 1 of the October 2008 General Permitted Development Order allows for "The enlargement, improvement or other alteration of a dwellinghouse" and then sets out in A.1 the specific circumstances where the development would not be permitted. This is expanded for properties on Article 1(5) land by A.2 for which it specifically removes the right to apply virtually any form of cladding. Condition A.3(a) which requires similar external finishes to those on the existing dwellinghouse clearly does not apply to all aspects of work undertaken in Class A and is obviously intended to relate to those circumstances in Class A that would result in an "enlargement". If it was the case that this condition did not allow for the application of cladding in any circumstances, there would be no reason to specifically exclude this for properties on Article 1(5) land in A.2. AN

A 2m high fence has been erected immediately adjacent to a private road and an agent claims it does not require planning permission. It does not look very attractive and we would like to take enforcement action against it. Can you advise? WN.

Under the provisions of Class A of part 1 of schedule 2 of the General Permitted Development Order 1995 a fence adjacent to a highway used by vehicular traffic over a metre high does requires permission. There is no definition of "highway" in the Order. In most cases a private road would not be considered a highway for General Permitted Development Order purposes. This is quite a difficult issue to determine but section 4.3442 of Development Control Practice considers this issue in some detail and reference should be made to that to decide the status of this particular road. The broad definition of a highway in this context is a way over which the public has a right to pass or repass. It is quite likely the agent is correct, therefore. JH.

Response

In 2000, and against officer advice, our council took enforcement action against a 2m fence alongside a private track.  On appeal, the Scottish executive reporter (as they were called then) concluded the private road was a track and not a road (being the term used in Class 7 of the General Permitted Development (Scotland) Order 1992).  His argument was on the same basis as your advice to WN, which also tallied with the original officer advice in the case.  Using the Roads (Scotland) Act 1984 definition, we include all public roads and footpaths under the description of what constitutes a road. SF.

Further Response

WN’s query related to England, but it is helpful to have a comment from a Scottish perspective. JH. 

A certificate of lawful development application has been submitted for a rear extension to a bungalow which is on article 1(5) land. The roof of the extension is pitched and would be cut into the roof of the main dwelling.  Class A.1(i)(iv) of part 1 of the October 2008 General Permitted Development Order amendment does not cover alterations to dwelling roofs and class B.1(e) precludes roof enlargements on article 1(5) land.  Does this mean the extension is therefore not permitted development?  The existing bungalow has a tiled roof and has no flat roof additions.  If the applicants proposed a flat roof, it is unlikely that the materials would be of a 'similar appearance' to those used on the existing dwelling. Would the extension therefore still need permission?  LH.

The Department of Communities and Local Government’s "Permitted development for householders – Technical Guidance" states "Where an extension to a house under Class A includes works that would require an alteration to the existing roof of the house (eg where the roof of the extension joins the existing roof), the alterations to the existing roof of the house will need to meet the requirements of Class B or C (as appropriate) in order to be permitted development." A roof enlargement on article 1(5) land cannot, as you point out, fall within class B, so the extension with the pitched roof would require planning permission. Ironically, the flat roofed extension which would presumably have a less attractive appearance would not require planning permission even if the top of the flat roof did not match the materials on the main house’s roof as the same guidance indicates, "Flat roofs will not normally have any visual impact and so the need for materials of similar appearance should not apply." JH.

My authority receives many enquiries about putting pitched roofs over existing flat roofs, mainly to attached garages or existing single storey rear extensions. Would these be considered under Class A or B of Part 1 of Schedule 2 of the General Permitted Development Order 1995 (as amended)? CT.

Class A1 (i) part (iv) of the Order precludes alterations to any part of the roof of the dwellinghouse from being in class A, so such alterations would fall into class B. Having said that, it does seem illogical that, say, a rear extension with a pitched roof can be added under class A, but, if one builds a flat-roofed rear extension and adds a pitched roof later, the roof then comes into class B. JH.

Response

Further to the question raised by CT on 20 March, section B.3 of part 1 of schedule 1 of the General Permitted Development Order 1995 (as amended) advises that the "resulting roof space" means the roof as enlarged taking into account any previous enlargement whether permitted by this class or not. Do the words "whether permitted by this class or not" imply that extensions under class A, that would create additional roof space should also be taken into account in assessing the 40/50 cubic metre limits for class B roof alterations? AN.

Further Response

This question has caused me to rethink what I said to CT. The reference to roof enlargements not permitted by class B could refer to:

a)    Roof enlargements that would have required planning permission such as a front dormer.

b)    Pitched roofs on extensions which connect to the main roof. On a conventional house these would normally be two-storeyed extensions.

c)    Pitched roofs on extensions which do not connect to the main roof. On a conventional house these would normally be single-storeyed ones.

Although the wording quoted carries over from the previous Order, I am not aware of any appeal decisions, etc which cover this issue. Having thought further on this issue, I consider the reference to roof alterations not permitted by class B would certainly refer to (a) and probably (b), but is unlikely to refer to (c). In view of this I now realize my answer to CT was probably wrong. It would seem adding a pitched roof to an existing single-storey extension is more likely to fall within class A, not B. I would be interested to know if any readers are aware of relevant appeal decisions or have views on this issue. JH.

My client wishes to extend a rural railway station which has been converted to a house where one elevation faces the former railway, now a permissive path, and the other faces the former car park area now part of the garden. The council considers the building has two 'principal elevations’, one facing the former track and the other facing the former car park. This severely restricts its permitted development rights. Is this correct? HI.

Part 1, A.1 (d)(ii) of last year’s General Permitted Development Order amendment refers to 'the' and not 'a' principal elevation of a dwellinghouse. Normally the use of the definite article would imply a dwelling could only have one principal elevation. The additional advice on the amendment published by the Department of Communities and Local Government and placed on the Planning Portal, however, advises, "The GPDO refers to ‘the principal elevation’ so the assumption is that there will be just one principal elevation" but then adds, "In some corner plots it may be that more than one elevation has the character of a principal elevation."  This advice makes answering your query quite difficult. Does it mean that houses can have two principal elevations or does it mean a corner house has just one but it is L-shaped? If the former interpretation is accepted, then the council in your case could be correct, but if the latter one is accepted then there cannot be two principal elevations on the opposite sides of a building. I would recommend making one or more certificate of lawful development applications and appealing if necessary. We would be interested to hear the outcome. This is yet another example of unclear wording in the Amendment causing interpretation difficulties. JH.

Response

I agree with the first part of the answer to the query: the use of the definite article makes it clear (unusually, in the General Permitted Development Order amendment) that a dwelling can have only one "principal elevation". It is sometimes hard enough deciding which one it is, without entertaining the possibility that there may be more than one. The Department of Communities and Local Government advice is confusing on this and other points, and is sometimes best ignored. MA.

Further Response

You may be correct, but it would be nice if the Order were clear on this issue. Good law is clear law. JH.

A householder wishes to construct an outbuilding directly adjacent to an existing rear extension. The previous permitted development requirements would have meant that if this building came within 5 metres of the house then it would have counted against the limits in class A, and in this case, because of the previous extension, would have required permission. I can find no such restriction in the new permitted development regulations. Is it correct that, provided the householder meets the dimension restrictions in part E, he can locate the outbuilding directly adjacent to the extension? In this case the householder would like to site the outbuilding 200mm from the existing extension with patio doors aligned with the patio doors on the extension allowing through access. From next door the outbuilding would appear as a single structure extending from the rear wall of the dwellinghouse. RL

You are correct. The 5-metre restrictions for outbuildings were introduced to the General Permitted Development Order a while ago to prevent scenarios like the one you describe. It seems a retrograde step that there are no similar provisions in the new amendment. JH.

Condition A.3 (a) of the new Class A introduced by the 2008 General Permitted Development Order Amendment states external materials have to be of similar appearance to those on the existing dwellinghouse.  Some authorities are interpreting this requirement to mean that an extension with a flat felted roof cannot be permitted development on a property that has pitched roofs, but some are not taking this view.  Who is right?  If it is the former would it be enough that there is at least some element of felted roof - on another extension for example, however small a part of the whole property this might comprise? PC.

My impression is, as you suggest, opinion is divided on this issue, yet another example of unclear drafting in the amendment order. Though I do not believe it definitive on this issue as the case relates to a different issue, in Burroughs Day v Bristol City Council (1996) it was decided that in assessing whether the external appearance of a building had been altered materially one normally considered this from the point of view of an observer on the ground. As a felt roof is not visible from the ground, I would favour the latter interpretation. If the former interpretation is correct, however, a felted flat-roofed extension could be permitted development if another part of the property also had such a roof. JH.

Response

Your response included a reference to the Burroughs Day case which was an over-simplification of what constitutes a material alteration: you said the courts held an appraisal should be from ground floor. Development Control Practice offers an excellent fuller summary, which says it depends on the degree of visibility, and in that instance the works were not visible from anywhere, save for distant office windows or the air. I think the test is the degree of visibility, not just whether you can see something on the ground. Bad design is bad design, if someone is going to be affected by it. JG

Further Response

Maybe I over-simplified the Burroughs Day case and thank you for clarifying this. With her comment JG sent an interesting appeal decision relating to a house extension in Sussex which was dismissed (DCS reference: 100-059-215). Although the extension’s appearance was acceptable from the street, it was of very poor design when viewed from a neighbouring property.

Since my original comment was published, the government has indicated it does not consider dormer roofs need to be covered with tile or slate. This is in a series of question and answers on the interpretation of the General Permitted Development Order Amendment which can be found at www.planningportal.gov.uk/uploads/clg-pd-faq.pdf. JH.

Class A.1 (c) of the recent General Permitted Development Order Amendment prohibits extensions exceeding the eaves height. How would you define this on a dwelling such as split level house? WM.

The frequently asked question document published by the Department of Communities and Local Government available on the planning portal website indicates the eaves height restriction would relate to the part of the dwellinghouse being extended from. JH.

As a raised platform is not permitted under either class A or E of the General Permitted Development Order (Amendment) 2008 does this mean garden decking now requires planning permission? PE.

A "raised platform" is described in the amendment as one higher than 300 millimetres, so decking below this height could fall within classes A or E. In most instances, however, decking would fall within class G relating to hard surfacing. JH. 

A bungalow has a single storey rear extension across the whole rear elevation of the property permitted in the 1990s. Could a side extension be built off this extension (only off this side extension, not off the side of the original property) under Class A1 (h) of last October’s General Permitted Development Order Amendment, if it did not have a width greater than half that of the original dwelling? CT

This raises similar issues to the previous question. Applying the logic set out in that answer, though this issue is not clear, I would say such an extension could be built as permitted development, provided it did not extend beyond more than 3 or 4 metres, as appropriate, beyond the original rear wall of the house. JH.

Our local council has adopted a very strict approach to lawful development certificates for domestic extensions which fall into two classes.  A standard 3 metre deep two-storey rear extension to a detached house with a pitched roof with the gable facing down the garden and its ridge running back into the original roof has been refused for such reasons.  Whether you take that part of the extension roof over that of the original house or indeed the entire extension roof volume, it is still below 50m³.  Surely there is a combination of classes here as if the roof cannot be considered permitted development under class A, it can under class B. Can you comment? ML.

This column considered similar issues on 28 August and 25 September last year. The conclusion was it is possible to consider whether proposals are permitted development by combining two or more classes. This is confirmed by the Department of Community and Local Government’s advice on the Planning Portal which states, in answer to a query on flues, that classes A and B do not grant permission for flues because they are covered by class G. Having said that I have found another appeal where an inspector considered classes A and B should not be combined (DCS No: 100-064-178).  Such reasoning makes it extremely difficult to build two-storey extensions as permitted development, however. I am therefore somewhat dubious of it, but this scenario is obviously not completely clear-cut. JH.

For a detached dwelling with opposing sides, one local council considers side extensions under class A, A1(h)(ii) of the October 2008 General Permitted Development Order amendment should be considered 'cumulatively’, i.e. the combined width of both side extensions should not have a width greater than half that of the original dwelling. The wording, however, suggests that this width restriction is applied separately to each extension. Your view would be welcome. HI.

The relevant wording of the amendment allows side extensions where "the enlarged part of the dwellinghouse would extend beyond a wall forming a side elevation of the original dwellinghouse" and would not "have a width greater than half the width of the original dwellinghouse". To me this very much supports your interpretation. There is no suggestion extensions should be considered ‘cumulatively’.  Whilst there are many ambiguities in the 2008 amendment, this does not seem to be one of them. JH.

Response

I can confirm that at least two local authorities in Essex have been taking the "cumulative" approach to assessing the lawfulness of single storey side extensions, but a recent appeal decision confirms HI's interpretation is correct (DCS no: 100-066-569 ). SH.

Condition A.3(a) of part 1 of the October 2008 General Permitted Development Order amendment requires that, apart from conservatories, dwelling alterations should use similar external finishes to those on the original house. In the light of this my authority considers replacing wooden windows with UPVC would normally require permission. I would appreciate your views on this. Are you aware of any appeal decisions which have considered this? AM.

The recently published Permitted Development for Householders Technical Guidance document states "it may be appropriate to include new PVC double glazed windows in an extension even if there are no such windows in the existing house. What is important is that they give a similar visual appearance to those in the existing house, for example in terms of their overall shape, and the colour and size of the frames."  This suggests that such proposals need to be considered individually and a "blanket ban" approach is not justified. I would make one comment on the guidance document; that in assessing similarity of materials the shape of windows and the size of frames should not be taken into account. Rather similarity of appearance should only be assessed on colour and texture. I am unable to trace any appeals where this issue has been considered. JH.

Does the 4-metre height limitation in A1(e) of class A of part 1 of the October 2008 General Permitted Development Order amendment just relate to single-storey rear extensions or does it also apply to single-storey extension extending beyond a principle elevation which does not front a highway?  Would a chalet-style extension with eaves above the ground-floor window head and with accommodation within the roof be single-storey or two-storey extension? Does planning legislation have a definition of "single-storey"? BH.

There is not a definition of "single-storey" in planning legislation, so the term would be interpreted in its normal everyday meaning. Within this context, I am sure an extension which was chalet-style or incorporated a first-floor dormer would be considered to be two-storey.  If you omit section (i) from A.1(e), it reads, "Development is not permitted by Class A if the enlarged part of the dwellinghouse would have a single storey and exceed 4 metres in height", so a single-storey front extension would be restricted to 4 metres height. Ironically, however, one could build a two-storey front extension (or taller if the house had more than two storeys) subject only to the limitations that the extension should not be above the highest part of the roof of the existing dwellinghouse (A.1(b)) and the eaves should not exceed the height of the existing eaves (A.1(c)). JH


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