Rural extensions Q & A DCP Section 12.6

This section covers development control issues in respect of dwellinghouse extensions in rural areas where countryside restraint policies affect the size, design and character of extensions. It includes the creation of additional living accommodation through alterations, such as basements and loft conversions. Additions to houses in conventional urban or suburban situations are dealt with in other sections of this group (12). Extensions to listed buildings in general are discussed at (27.3), curtilage buildings at (12.8) and garden extensions at (12.9). Extensions involving granny annexes are considered at (10.2).

Q & A    12.6/10

A detached farmhouse was partly demolished in the 1970s leaving 75% of the original. This probably occurred for safety reasons. A two-storey extension has now been commenced which is larger than the relevant PD tolerances. However, with the new extension the total dwelling would be smaller than that of the "original" dwellinghouse as on 1/7/1948. Can you confirm that planning permission is required?

The GPDO allows the "original dwellinghouse" to be extended by 70 cubic metres or 15% whichever is the greater. As the base date in this case, as defined in the Order, is the appointed day one would have to look at the dwelling as it was then to make the necessary calculations. Even with a larger dwelling to play with than now exists, it seems unlikely this new extension would be less than 15%.


The 15% formula is to be applied to the resulting building which would be the farmhouse as now plus the proposed new extension. Comparing this resulting dwelling with the 1948 dwelling it would seem that the proposed extension would be permitted development.

It is generally accepted that the removal of unsightly buildings as part of a development proposal in the countryside can be a planning gain and thereby improve the chances of approval. However, I am dealing with a case where a client wishes to extend a converted barn, where at the time of conversion two years ago a large obtrusive building was removed as a necessary part of the works. The proposed extension would occupy barely a fifth of the footprint of the original unsightly building and would also be significantly less visible. Do you think that it is reasonable to argue that the planning gain achieved from the earlier removal is a factor in favour of the current proposal?

I do not think that it is reasonable to pursue this argument as any planning gain that might have been derived from the removal of this building has already been spent.

My client wishes to enlarge a modest un-extended agricultural dwelling in open countryside to a scale that is likely to conflict with local plan policies. I think a way round this problem would be to first secure permission for an extension within policy limitations. Then, having used up his permitted development rights for an extension and detached outbuilding, he could implement the permission and link the developments together. While this exposes deficiencies in the General Permitted Development Order 1995, is it flawed?

Although others have claimed to use this tactic, I remain sceptical about its practicability. It would appear necessary to obtain permission for either a 5m extension to the dwelling, which in my experience would normally be considered excessive, or for a free-standing outbuilding at least 5m long to link an extension and curtilage building that would first need to be erected as permitted development. While an outbuilding built under Class E, Part 1, Schedule 2 of the Order could be used for primary residential purposes, it could not be built for this use in the first instance. Moreover, to pre-empt the scenario you outline, I recall having seen a cleverly worded condition that either sought to proscribe implementation of a permission for a house extension in the event that an adjoining outbuilding was erected or to prevent it from being joined to such a building. So the intended outcome might prove difficult to achieve.

An appeal has recently been dismissed for a single-storey extension to a detached dwelling in the green belt as inappropriate development. It was found that although it did not harm the character of the building, it would harm the openness of the green belt despite being screened. PPG2 states that the construction of new buildings inside a green belt is inappropriate, but one of the exceptions is the limited extension, alteration or replacement of existing dwellings provided that it does not result in disproportionate additions over and above the size of the original building. The extension or alteration of dwellings is not inappropriate in the green belt". In this case the sum of the previous extensions to the building is approximately 40 percent and the proposal would make the cumulative increase 48%. This increase is not "over and above the size of the original building", rather it is physically smaller? PG.

You are not the first practitioner to be confused by the wording of PPG2.. However, in the case of the term "over and above the size of the original building" in practice this has always been taken in a restrictive sense as relative to the size of the dwelling as constructed or existing in 1948. Thus a 48% increase in dwelling size since that time could be viewed as ‘disproportionate’ and thus "inappropriate".  The latter term implies a blanket policy restriction which cannot be overcome by arguments that the building concerned cannot be seen or is unobtrusive. GH.

I am considering options for extending a dwelling in the green belt.  It has two attached barns and these and the house existed in 1948. Although neither the dwelling nor the barns have been extended, both barns have been converted into additional accommodation for the dwelling.  The council says the change of use of the barns already constitutes a ‘disproportionate addition’ to the dwelling and therefore no physical extension to it will be permitted. Is this a reasonable bearing in mind that throughout this time the openness of the green belt has not been physically affected? PS.

Paragraph 3.6 of Planning Policy Guidance Note 2 advises extensions to dwellings in the green belt are appropriate if they do not result in disproportionate additions to the original dwelling. The policy’s purpose is to maintain the green belt’s openness. My personal view is if a house has been significantly extended by change of use without harming the green belt’s openness, it seems reasonable to oppose actual extensions which would harm this openness. A couple of other people I discussed this issue with supported your view, however! If you lodge an appeal, we would be interested in the outcome. Even though you might not get permission for further extensions, the dwelling probably could be extended using permitted development. JH.

Planning Policy Guidance Note 2 restricts dwelling extensions in the green belt to protect its openness, but last year’s General Permitted Development Order Amendment allows substantial additional extensions, after an application for extension has been allowed, so a property could be vastly over-extended. In an appeal decision in Staffordshire that has come to my attention (DCS No 100-064-270), an inspector accepted the need to remove permitted development rights by condition when allowing an extension to a green belt dwelling. In that case, removing the rights was supported by supplementary planning guidance, but the issue is a national one. Although circular 11/95 says that permitted development rights should only be removed exceptionally, do you think a similar condition to the Staffordshire case could be used as a matter of course? MK.

In my experience inspectors are willing to accept conditions removing permitted development rights if there are good reasons for imposing them and they only remove appropriate rights. For instance, in the appeal you quote, the inspector varied the original condition so it only took away rights for extensions and outbuildings, but not other rights. Each case needs to be considered on its own merits. To take an obvious example, if permission is just sought for a porch, it would be inappropriate to take away permitted development rights. In the case you cite, however, the extensions which resulted in the council imposing a condition taking away permitted development rights increased the size of the dwelling by 24% If removing conditions is supported by development plan policy (any such policy should specify the particular types of circumstances in which it would be applied), this of course means an inspector would be more likely to accept it. JH.

I have recently read an appeal decision regarding a single storey domestic outbuilding within the green belt in Gloucestershire (DCS no: 100-067-925) which was refused as it would constitute a disproportionate addition to the original dwelling so would not constitute a ‘limited extension’. The inspector dismissed the appeal, but reached a different conclusion to the authority’s as she considered the outbuilding was not an extension so would not fall within any of the building categories acceptable within green belts listed in Planning Policy Guidance 2. I interpret the inspector’s approach to mean householders must demonstrate ‘very special circumstances’ for any green belt domestic outbuildings. This seems onerous so the reasonable and pragmatic approach would be to class outbuildings as extensions for green belt purposes. What is the correct stance on this?  PR.

This issue was considered in the case of Sevenoaks District Council v Secretary of State for the Environment and Dawe (1997) where the council challenged a permission granted on appeal for an extension to a detached garage in the green belt and the inspector treated it as being a reasonable extension and therefore appropriate development. The judge commented, "The Inspector was fully entitled to hold that the garage was part of the ‘dwelling’, in the sense that it was a normal domestic adjunct, and thus to treat the appeal proposal as an extension of it. The words ‘extension... of existing dwellings’ are certainly capable, in my judgment, of having that meaning, and he was entitled to form his opinion in determining this matter in that way. The garage is an important domestic adjunct, just as the coal shed was in earlier days, and for example, an outside playroom often is. The mere fact that any of these uses is physically separated from the main house does not prevent them from being part of the dwelling. It is a matter of fact and degree in every case and, for example, if the garage had been at the bottom of the garden, the Inspector would doubtless have taken a different view." In the appeal decision you cite, the inspector does not address the issue whether the outbuilding should be considered as an extension for green belt purposes, but rather says simply because it is an outbuilding it is inappropriate development. This does seem to contradict the Sevenoaks judgment. JH.

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