Appeal 3367063

The appeal is dismissed.

Since the appeal was submitted, the Council have granted planning permission1 for external window and door alterations to existing dwelling, conversion of existing garage in order to facilitate provision of habitable accommodation and removal of part of the existing render to front and side elevations. This decision was issued on 20 November 2025 and so could not have been provided at the time of the appeal. I have had regard to this decision as a material consideration. However, I am satisfied that no prejudice arises to any party as a result of this. I will return to this matter later in my decision.

The main issues are: • whether the development would constitute inappropriate development in the Green Belt having regard to the National Planning Policy Framework and relevant development plan policies; • the effect on the proposed development on the openness of the Green Belt; and • if it is inappropriate development, whether the harm by reason of inappropriateness, and any other harm, would be clearly outweighed by other considerations, so as to amount to the very special circumstances necessary to justify it. 1 Planning Application Ref: 25/00950/FULHH

The appeal site lies within the Green Belt. The National Planning Policy Framework (the Framework) states that the fundamental aim of Green Belt policy is to prevent urban sprawl by keeping land permanently open. It further explains that inappropriate development is, by definition, harmful to the Green Belt and should only be approved in very special circumstances.

The Framework further establishes that the construction of new buildings in the Green Belt should be regarded as inappropriate, subject to a number of exceptions listed in Paragraph 154 of the Framework. One such exception being the extension or alteration of a building provided that it does not result in disproportionate additions over and above the size of the original building.

Policy HS5 of the Chorley Local Plan 2015 (CLP) states that permission will be granted for the extension of dwellings in the Green Belt provided that the proposed extension does not result in a disproportionate increase in the volume of the original dwelling. Whilst the Framework does not define “disproportionate,” Policy HS5 considers increases of up to 50% (by volume) acceptable. Although this adds detail beyond the Framework, it remains consistent with it. However, determining whether an addition is disproportionate is ultimately a matter of planning judgment, not just a numerical calculation.

The Framework defines an ‘original building’ as a building as it existed on 1 July 1948 or, if constructed after 1 July 1948, as it was built originally. The figures provided by the appellant state that the ‘main house’ had a volume of 275.3m3, before substantial extensions were added in the late 1970s totalling 370.4m3. These taken with the existing shed and greenhouse amounts to an overall volume of 671.07m3. However, the 1970s extension post-dates 1948 and cannot be included in the original dwelling calculation. Similarly, there is no evidence that the shed and greenhouse formed part of the original building, so they should also be excluded.

The appellant refers to historical mapping and aerial photographs as evidence of outbuildings within the property grounds. An OS Map from 1929 shows two detached buildings behind the appeal property. A 1959 [name] and a 1960 aerial image also show two buildings, though with different footprints. These buildings no longer exist, but the appellant uses these documents to calculate the total volume of the “original building,” stating that these outbuildings should be included.

The appellant estimates the volumes of these buildings as 299.53m3 for the larger and 55.29m3 for the smaller, giving a combined original volume of around 634m3 when added to the main dwelling. The appellant’s calculations are based upon an assumption that the larger building was two storeys high, with a pitched roof. However, I acknowledge that the calculations have not made any allowance for roof space, to be on the conservative side.

Whether or not outbuildings can be regarded as an extension to the dwelling is a matter of planning judgment. The Warwick Case2 established that Paragraph 149(c) (now Paragraph 154(c)) “is not to be interpreted as being confined to physically attached structures but that an extension for the purposes of that provision can include structures which are physically detached from the building of 2 [name] v SSLUHC, [name] & [name] [2022] EWHC 2145 (Admin) which they are an extension”. Caselaw3 has also established that for a residential outbuilding, it would be reasonable to take into account whether the building was a “normal domestic adjunct”.

Whist historical mapping confirms the presence of additional buildings; there is no substantive evidence that they were in residential use or functioned as extensions of the main dwelling. Even if they did, the evidence from maps and photographs is inconclusive, making it impossible to accurately determine their size or volume as of 1 July 1948. Furthermore, some calculations rely on evidence post-dating 1948. For these reasons, I am not persuaded that the outbuildings formed part of the original building.

Turning to whether the proposed extensions would be a disproportionate addition, it is not disputed that the original building has been substantially extended with extensions carried out in the late 1970s adding approximately 370.4m3 to the original building. Based on my above findings, these extensions cumulatively amount to substantial additions to the original building. Therefore, even though the size of the proposed extensions is modest when compared to previous extensions to the building, they cannot be considered in isolation and the total size of the existing and proposed extensions combined, would result in a significantly larger building. Accordingly, the proposed development would not meet the exception set out in Paragraph 154(c) of the Framework.

The appellants have contended that the development might also be considered to fall under the exception to inappropriate development at Paragraph 154(g) of the Framework, relating to the partial or complete redevelopment of previously developed land. The property is not in a built-up area, therefore, the residential garden, where the extensions would be located, could fall within the definition of previously developed land, in Annex 2 of the Framework. However, with the exception of the replacement of the front porch, the proposed development would mostly comprise of extensions and alterations to an existing building. Consequently, when considered as a whole, the proposal does not amount to the partial or complete redevelopment of previously developed land.

The updated Framework has introduced the concept of grey belt land. However, even if I were to accept that the appeal site does not strongly contribute to the purposes of the Green Belt relating to unrestricted sprawl, the merging of towns or the setting of historic towns, in order for development not to be regarded as inappropriate, Paragraph 155 of the Framework refers to the use of grey belt land to meet a demonstrable unmet need for the type of development proposed. No evidence has been submitted to indicate that this is applicable in this appeal. Consequently, this paragraph does not render the development not inappropriate.

For the reasons given above, I conclude that the proposed development would be inappropriate development in the Green Belt as a result of a disproportionate addition over and above the size of the original building. As such, it would be contrary to Policy HS5 of the CLP and the Framework. 3 Sevenoaks District Council v Secretary of State for the Environment and Dawe (1997)

Paragraph 142 of the Framework states that the fundamental aim of the Green Belt is to prevent urban sprawl and keep land permanently open. Openness has both spatial and visual dimensions.

The proposed extensions would be located to the front and side of the existing dwelling and as noted above, are relatively modest in size, scale, and bulk. Nevertheless, they would increase the volume and massing of the building, resulting in a harmful loss of openness both visually and spatially, albeit to a limited degree given the scale of the proposal.

Therefore, I conclude that the proposed development would not preserve and would have a harmful effect on the openness of the Green Belt, contrary to Policy HS5 of the CLP and the Framework.

The consideration of a fallback position, including what could be carried out under permitted development rights set out in the Town and Country Planning (General Permitted Development) (England) Order 2015 (the GPDO), is a well-established principle. I have no reason to believe these rights do not exist and have considered the appellant’s suggestion that the property could be extended with a single-storey side extension and a rear dormer window. The appellant states these would result in a greater volumetric increase than the appeal proposal and that further outbuildings could also be added.

However, I have not been presented with any compelling evidence to lead me to conclude that there is a reasonable prospect of an extension or outbuildings being built under these provisions. Furthermore, I have also not been provided with any compelling evidence that these would have a similar effect on the Green Belt as the proposed scheme. Accordingly, I afford limited weight to this fallback position.

The appellant has indicated that the Central Lancashire Rural Development Supplementary Planning Document would support a replacement dwelling which could be up to 30% larger in volume terms than the existing property. Nonetheless, I do not have any reasonable evidence to suggest that the appellant would seek to erect a replacement dwelling. In any event, I have determined the appeal proposal that is before me and considered it against local and national Green Belt policies. For these collective reasons, I do not afford this matter significant weight in favour of the proposal.

I have also had regard to the recent grant of planning permission for external window and door alterations to existing dwelling, conversion of existing garage in order to facilitate provision of habitable accommodation and removal of part of the existing render to front and side elevations. However, this scheme did not any include any of the proposed extensions. Accordingly, it does not alter my above findings.

The proposed development constitutes inappropriate development in the Green Belt to which I attach substantial weight. The Framework indicates that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. It further states that very special circumstances will not exist unless the potential harm to the Green Belt by reason of inappropriateness, and any other harm, is clearly outweighed by other considerations.

In summary, the proposed extension, combined with previous extensions, would be inappropriate development in the terms set out by the Framework and would result in a harmful loss of openness to the Green Belt. The Framework requires that substantial weight should be given to any harm to the Green Belt. The other considerations advanced in support of the appeal carry no more than limited weight and thus do not clearly outweigh the harm I have identified. Consequently, the very special circumstances necessary to justify the proposal do not exist thus it would fail to accord with the Green Belt aims set out in Policy HS5 of the CLP and the Framework.

For these reasons, the proposed development would conflict with the development plan, and the material considerations do not indicate that the appeal should be decided other than in accordance with it. Therefore, the appeal is dismissed.