The General Permitted Development Order Part - 1 Class C 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 C 4.34/104

I am dealing with a case regarding the installation of rooflights into a barn conversion where Part 1 and Part 2 permitted development rights had been removed by condition. My opinion is that rooflights are an alteration to the roof normally covered by Part 1 Class C, and therefore the rooflights will require planning permission. Is my understanding correct?

Before considering the operation of the General Permitted Development Order 1995 it is important to clarify whether there is "development" in the first place.  The Town and Country Planning Act 1990 provides that works that do not materially affect the external appearance of buildings are not development, and the courts have held that part of this test involves the degree to which the works are visible from public vantage points.
Therefore, in the case you quote, your council first needs to form a view on whether the offending roof lights require planning permission at all. If it is judged that they do, the removal of  Part 1 Class C rights precludes any possible deemed permission. As noted in Circular 9/95 paragraph 42 this Class permits rooflights provided there is no material alteration to the dwellinghouse shape.

We are currently looking at a proposal to install solar panels on a dwellinghouse. The panels will cover 30% of the south facing roof slope, and project above the roof by approx 60mm. Any views on whether this will be permitted development under part 1 class C of the General Permitted Development Order 1995? BC

This question raises much the same legal issues as discussed in Forum 13 September 2002 p19 with regard to roof lights. Here a case was quoted where an inspector conceded that a roof light which was "slightly protruding" above the plane of a roof was not a class B "enlargement", but neither was it a class C material alteration to the shape of a roof. Consequently the roof light was considered to be permitted development.


I believe that there is a material difference between solar panels and roof lights. Although on the face of it, a single solar panel might appear not dissimilar to a roof light, it will be likely to be physically attached to the roof,  rather than being an inserted part of it. A strict interpretation of C Class B would therefore suggest that a solar panel could be viewed as an "enlargement" extending beyond the plane of a roof slope. If fronting a highway express permission would therefore be required. Importantly for conservationists all such panels would be brought under control in conservation areas and areas of outstanding natural beauty.

Further light is thrown on this subject by a case reported and illustrated in (Planning 1 February 2002 p19) where an inspector considered a case involving enforcement against solar panels in the roof of a house in Swanage. After ruling that the panels were development he considered that part 1 Class B did not apply because the operations were not an enlargement of a dwelling consisting of an alteration or addition to its roof. The inspector concluded that the development should be considered under Class C and accepted a local authority argument that the panels projected far enough beyond the plane of the roof to materially alter the shape of the dwellinghouse. He noted that the panels projected between 8cm and 12cm from the roof, which was appreciably more than the projection of a flat window.

Any assessment on this question clearly remains a matter of judgment to be determined on the merits of each case. However, it is worth noting that wording of Class C refers to a material alteration to the shape of the entirity of the dwellinghouse, and not the appearance of the roof viewed alone. Taking that general view of the house in the Swanage case I cannot help feeling that this inspector’s view was on the strict side, although I am sure that the courts would hold that it was a view he was entitled to come to.

In considering proposals for solar panels to dwellinghouses in conservation areas and having regard to Class C, Schedule 2, Part 1 of the GPDO 1995, should my authority decide whether such a proposal would constitute a material alteration to the shape of the dwellinghouse in each case or request an application for permission, regardless of the number of panels proposed or their surface area coverage?

This matter is discussed generally at 4.34 of Development Control Practice. In addition, the annex to PPG22 issued in 2002 contains limited guidance on photovoltaic (PV) cells, which convert solar radiation to electricity. It explains that where it is proposed to install these on an existing building, an authority should decide whether they would be a "material alteration to the external appearance of the building". If not, then permission will not be required. But even if the authority considers that it would, express planning permission may not be required because of the rights conferred under the GPDO.

In conservation areas, the guidance says that if PV cells are fitted to a dwellinghouse roof so that in the authority’s view they do not project significantly above the existing roof plane, a planning application may not be necessary, which I take to be an allusion to Class C. It also points out permitted development rights to enlarge the roof of houses do not apply in conservation areas.

Thus solar panels within a conservation area fitted flush with the roof will be permitted development under Class C, irrespective of their surface area, but where they would project significantly above a roof slope permission will be required, as they do not fall within either Class B or Class C, Part 1, Schedule 2 of the GPDO.

My council has a draft UDP policy requiring new development to contribute to public art. An application has been submitted recently for a 'mural' painted on high-level panels to be fixed to the side of a building. Does this require permission and how best should a decision on what constitutes development be made? In addition, as the council has no funds itself to erect public art it aims to persuade developers through sec 106 agreements. Should any supplementary planning guidance include the criteria and formula that should be used?

In Windsor and Maidenhead Royal Borough Council v Secretary of State for the Environment [1988] it was held that the painting of a building was capable of being a building operation and required permission where it had a material effect on external appearance. However, unless permitted development rights are withdrawn by planning condition or an Article 4 Direction, this is granted by Class C, Part 2, Schedule 2 of the GPDO, regardless of the building’s use. This does not apply to Scotland, where all murals require permission. Control over a mural is therefore normally exercisable only where it has the purpose of advertisement, announcement or direction, or affects the character of a listed building. But in this particular case, the fixing of painted panels to the building would exclude the mural from being permitted development.

Many authorities have adopted supplementary planning guidance on the provision of public art, based on the former Arts Council of Great Britain Percent for Art campaign of 1988, some of which are posted on their websites. Typically, guidance aims to secure 1% of the capital costs of major development schemes to be used for publicly sited works of art, sets out the criteria for assessing eligible schemes, the methodology and procedures to be followed, and how such provision is to be achieved. This may be by negotiation, planning condition or through s106 agreements.

My authority is unsure about the need for permission for domestic balconies when these are formed by railings on an existing flat roof or by the replacement of first floor windows by double doors with railings outside, or through dormer windows with double doors and security railings. I think that providing the railings do not exceed 4m in height above ground level, permission is not required and that the cubic capacity is only in the railings themselves. Can you please clarify?

In R. (on the application of Cousins) v. London Borough of Camden [2002], it was held that the erection of iron railings above a flat roof fell to be considered under Class C, Part 1, Schedule 2 of the GPDO 1995. However, dormer windows with protective railings will constitute an addition or alteration to the roof which should be assessed against Class B. The replacement of first floor windows and the erection of outside railings to form a balcony is likely to materially affect the external appearance of the dwelling and be considered a building operation, to be judged against the limitations under Class A. The 4m height rule applies only to development considered under this class. But you are correct in your understanding that, for the purposes of Class A, the additional volume created amounts only to that of the railings themselves. This means that balconies are often exempt from planning control, as acknowledged in last year’s review of permitted development rights, which recommended that they be excluded from a revised version of the Order.

A householder was granted permission for a two-storey rear extension which was then built. Following complaints, the planning authority argued that as roof lights were installed in the roof to the extension, before it was completed as approved, the householder could not rely on the rights under Class C, Part 1, Schedule 2 of the GPDO 1995. A new permission was therefore necessary to retain the roof lights and this was granted subject to a condition requiring the use of fixed panes and obscure glazing. However, as the view from the roof lights is restricted by their position and tree screening, they do not overlook property less than 18m away. If an appeal is lodged against the condition, could the decision affect the whole permission?

Under sec 79 of the 1990 Act, the Secretary of State is able to determine an application as if it had been made to him in the first instance. He may therefore reverse or vary any part of the planning authority's decision whether the appeal relates to that part or not, or it relates only to a condition. The theoretical possibility of losing the permission altogether could only be avoided if, instead of appealing the authority's decision, the householder were first to apply for the condition to be removed under sec 73 of the Act and, if that is refused, appeal to the Secretary of State. However, in this case, I think it highly unlikely that an inspector would reverse the authority’s decision completely and refuse permission. Instead, I think that the inspector would either allow the appeal and delete the condition, or dismiss it but grant permission with a similar condition.

Is permission required for the removal of a chimney stack on an unlisted dwellinghouse? Does such a proposal constitute an alteration to the shape of a roof as outlined in Class C, Part 1, Schedule 2 of the General Permitted Development Order 1995? It is difficult to find guidance on whether chimneys should be classed as part of the roof or should be treated independently. Would it be reasonable to ask for an application purely on the grounds that the loss of the chimney would result in a material alteration to the external appearance of the dwelling?

PPG15 confirms that chimney stacks form part of a building’s "roofscape". Applying the principles established following the judgement in Shimizu (United Kingdom) Ltd v. Westminster City Council [1997], the removal of a chimney stack on an unlisted building outside a conservation area would be an alteration that falls to be assessed under the provisions of  Class C. But I think it follows that where this would result in a material alteration to the shape of the dwellinghouse, it would require express permission. Class C generally only permits the re-covering of a roof and the insertion of windows or solar panels that do not project significantly above the plane of the roof.

My authority is debating the circumstances in which solar panels require permission. My research makes it clear that the projection from the roof slope and size of the panel is important in determining whether it is permitted under Class C, Part 1, Schedule 2 of the General Permitted Development Order 1995, with a projection of 8cm to 12cm sufficient to materially alter the shape of the dwelling. Invariably, my officers find that such panels require permission because they are not fitted flush with the roof slope and materially change the shape of the roof. What is your advice?

Guidance is set out in technical annex 6 of the companion guide to PPS22. Paragraph 13 says that in general solar panels should be encouraged. Provided the panels are not of an unusual design, do not involve a listed building and are not in a designated area, they should be regarded as permitted development. Although it has no legal force, the guide indicates that solar panels should be treated as being within the plane of the existing roof slope for the purposes of Class B1(b), Part 1, Schedule 2 of the Order. This is a more permissive approach than that previously taken by inspectors and councils, as detailed in Development Control Practice 4.3. They tended to consider panels against Class C and to require applications where they would result in a material alteration to the shape of the dwellinghouse.


In concluding that permission is invariably required for solar panels because "they materially change the shape of the roof", The questioner has applied the wrong test. Class C, Part 1, Schedule 2 of the General Permitted Development Order 1995 says that they should not cause a material change to the shape of the "dwellinghouse". This is a different criterion from the one applied in Burroughs Day v Bristol City Council [1996], where a roof extension behind a parapet wall and other alterations were held not to be development because they did not materially affect the appearance of the building as a whole, even though they may have affected the appearance of parts of it.

Further Response

I am confused by this advice. What weight should be afforded to the companion guide to PPS22? Is this merely guidance as to how the Order should be interpreted?

Statements of Government policy, such as those in PPS22, are material considerations to be taken into account in decisions on individual applications. The courts have held that the weight afforded to any such consideration is entirely for the decision-maker. While paragraph 1.10 of the companion guide is a convoluted disclaimer to the effect that the Secretary of State will not be bound by its contents, its precise status is unclear. However, I do not see how it can carry the same weight as the policy statement itself. Technical Annex 8 to the guide has no statutory force and merely offers advice on how the Government expects the Order to be interpreted by planning authorities when dealing with proposals for solar developments.

Initially my authority thought that the advice in the annex that solar panels should be treated as being within the plane of the existing roof slope for the purposes of Class B.1(b), Part 1, Schedule 2 of the GPDO was a helpful clarification. However, it has proved difficult to justify why permission is needed inside a designated area but not outside it. Surely it is unreasonable to tell an applicant that a solar panel on a dwelling outside a conservation area is considered to fall in Class B.1(b) but if it is within such an area it does not? Has this been tested at all?

I cannot see where the difficulty lies. The guidance does not alter the fact that while there may be no breach of Class B.1(b), solar panels in a conservation area would still be caught by condition B.1(e).

I cannot see why such panels should be assessed under class B, which relates to the "enlargement of a dwellinghouse consisting of an addition or alteration to its roof". It is clearly aimed at roof extensions and dormer windows that increase living space. Solar panels are no more an enlargement of a dwellinghouse than stone cladding or the replacement of slates by concrete tiles, although they all marginally increase the bulk of the building. So surely they fall within class C, which refers to "any other alteration to the roof of a dwellinghouse". Provided the panels would not project significantly beyond the roof plane, they would not need planning permission. Although I suspect that there is a tendency for local planning authorities to grasp the opportunity to control solar panels under class B of the Order, I cannot see any legal basis for this. Do you agree and has anyone appealed against the refusal of a lawful development certificate on this yet?

As noted in my reply, there is an inconsistency between the approach advocated by the guide and that normally taken by inspectors, who have tended to consider panels against class C and to determine that permission is required where they would result in a material alteration to the shape of the dwellinghouse. It has been held that a roof light "slightly protruding" above the plane of a roof was not a class B "enlargement" and that solar panels projecting more than 8cm above the roof slope required permission. The advice in the DCLG guide clearly encourages a more permissive approach. This is because whereas a panel projecting above a roof slope might appear to require planning permission when judged under the provisions of class C, they are likely to be permitted development when assessed as an addition or alteration under class B. However, I have not seen any recent case where the guidance in the companion guide has been tested. 

My authority has taken the position that solar panels inserted in the roof slopes of dwellinghouses fall within class B. However, this seems at odds with appeal decisions and my own view that they should be considered under class C because they do not enlarge the house. Neither the companion guide nor my authority offers any explanation as to how solar panels enlarge a dwelling. The advice in the guide is confusing for both planners and members of the public.

Schedule 2 part 1 class C of the General Permitted Development Order 1995 as amended allows alterations to the roof of a dwellinghouse such as the installing rooflights or re-tiling without planning permission. However, would Class C extend to the replacement of a thatched roof with a slate or tiled roof? MP.

Under the provisions that applied before last October work under class C was not permitted if it resulted in a material change to the shape of the dwellinghouse. As a thatched roof is thicker than a slate or tiled one, this provision would normally have precluded such work from being permitted development. There is no such provision in the new amendment, however, nor is there a provision requiring external materials to be similar to existing ones as in classes A and B. Thus, replacing a thatched roof with slate or tiles would be permitted under class C. JH.

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Sign up now
Already registered?
Sign in

Join the conversation with PlanningResource on social media

Follow Us:
Planning Jobs