Should we build a new house in our garden or extend?

Q: We have some extra land adjacent to our garden and also some unwanted space in the garden. It is enough to build another dwelling on. Access to the new dwelling would be via a road which leads around to the garages on the estate....The council planning officer said informally over the phone that since the access drive was unlit and rather rough, they would not grant permission for a new dwelling.....I am now therefore thinking in terms of extending the house with a 2 storey extension. However I am not clear whether in a semi detached / end of terrace house like ours, the extension can go the full width of the house or if a gap has to be left between the new extension and the fence of the adjoining semi. I hope you or your planning expert can cast some light.


There has been concern about ‘garden grabbing’ for building new dwellings in recent years and current national planning policy guidance is generally not supportive of parts of gardens being hived off in order to create new dwellings. However, if you have land next door to your garden that you own and can be reached by an access, then there may be scope to explore creating a new house here. It would be important to consider whether creating a new dwelling here would have any significant impact on your neighbours and their enjoyment of their property, particularly in terms of additional overlooking, an increased sense of enclosure, loss of light and more noise and disturbance. Any new dwelling would also have to be designed to create satisfactory living conditions in terms of room sizes, layout and outdoor amenity space. The fact it might not front an adopted (i.e. maintained by the Council) road should not preclude the principle of building a new dwelling. The highway department will consider the suitability of the access road and may well require improvements to it, paid for by yourself, but this could be done as part of an agreement accompanying any planning permission. A specialist highway engineer would be able to advise further on this point. If you did consider going further, then I would recommend a formal pre-application with the Council presenting some initial plans to discuss with them.

Turning to the permitted development rights for your property, the Government has made these more generous for a temporary period (currently until May 2016) in respect of single storey extensions, although there is a neighbour notification process if you wish to use the more generous rights. If you live in a conservation area; Area of Outstanding Natural Beauty; a National Park; in the Broads or part of a World Heritage Site, then a two storey extension will always need planning permission as two storey rear extensions do not benefit from the permitted development rights in these areas. If you live outside these areas, the criteria for a two storey extension to be built as permitted development are that it must not extend more than 3 metres beyond the rear wall of the original house (as it was in 1948), must be no closer than 7 metres from the rear boundary and because you are an attached property, the maximum eaves height of an extension (where the wall meets the roof) can be no higher than 3 metres within two metres of your boundary with your neighbour. This last criteria could have quite an impact on what you can do. Other criteria include matching to roof pitch of the house. I often recommend applying for a Certificate of Lawfulness when considering undertaking permitted development in order to have comfort that what you are about to build does indeed fall within the permitted development rights. Of course, if what you would like to do isn’t permitted development it doesn’t mean that you will not be able to do it but it will require you going through the planning application process.

Simon Wallis BA Hons MRTPI
Director, Planning, Savills


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