Adding storeys to an existing building will generally require planning permission and may require other consents, including building regulation approval and, if your property is listed, listed building consent.
Applications for planning permission are assessed against planning policies adopted by your local planning authority, but also against other matters such as guidance produced by Government. There is a trend towards such guidance and policies supporting upward extensions.
In London, the draft London Plan suggests that Boroughs should apply a presumption in favour of the upward extension of flats, non-residential buildings and residential garages to provide additional housing, whereby such planning applications should be approved unless they give rise to an unacceptable level of harm. The presumption does not apply to listed buildings (and their settings) and conservation areas however, and other exceptions and conditions apply, including the requirement to comply with any design code produced by the relevant Borough for small housing sites. The draft Plan is currently undergoing examination and the policy remains subject to change before adoption.
Recently adopted government policy also supports opportunities to use airspace above existing residential and commercial premises for new homes, particularly where such development would be consistent with the prevailing height and form of neighbouring properties and the overall street scene, is well-designed and can maintain safe access and egress for occupiers.
There are already “permitted development” rights to enlarge, improve or alter existing homes to provide additional living space, but these do not currently allow for the addition of further storeys. The Government is considering also making such upward extensions “permitted development”, which means that a full planning application would not be required provided certain conditions and requirements are met. Instead, a more limited application for “prior approval” of specific matters would be required, although in this case the Government is proposing a long list of such matters – covering issues including design and the impact on the character of the local area and on existing occupiers and businesses.
Height limits in such scenarios are particularly contentious. The Government has proposed either that owners would be able to extend up to the height of the main roofline of the highest building in the terrace or, alternatively, to the prevailing roof height in the locality (which the local authority would need to determine). A maximum of 5 storeys from ground is under consideration, with new storeys of up to 3 metres in height, although there is concern about how the limits would apply in sloping streets.
The right would apply to residential premises and may be extended to other types of premises. It is not proposed to introduce permitted development rights in respect of listed buildings, conservation areas or other protected areas such as national parks or areas of outstanding natural beauty.
So will I get permission for my proposed upward extension?
Whether you can obtain planning permission for additional storeys to provide new homes will depend entirely on your property and the area in which it is located. National and local planning policies and guidance may provide high level support, but much will turn on the detail of the proposal. Even if permitted development rights are introduced and apply, obtaining prior approval may not be straightforward.
If your property is suitable for upward extension, critical to success will be a high quality design demonstrating careful consideration of the impact of the development on existing occupiers and neighbours and the street scene. Investing in a good architect will pay dividends.
Advice should also be sought in advance on any other approvals required and other development requirements and costs. These may include the community infrastructure levy which is payable on new floorspace in certain circumstances. Also, national and local policy on “section 106 obligations” should be checked – such obligations could require financial contributions or works.