House extension boundary

Many house extensions will be close to a boundary. Many Local Planning Authorities have rules, policy or planning guidance on house close a house extension can be sited to a boundary.

As a general rule, most single storey extensions can be built up to the sites boundary while the first floor element of any two storey extension must have a minimum of a 1M gap. This general requirement is meant to prevent terracing where previously detached or semi detached properties would become one mass or block if they were all allowed to abut together along the street.

Therefore, incorporating gaps between existing properties is a very important feature of most LPA’s. The house extension boundary distance can also be greater than 1M if the area is already spacious that has wide plots with existing larger gaps between the properties. Most Planning Authorities will want to maintain the spaciousness character of the area.

There will be exceptions to maintaining a gap for a house extension boundary but it is the applicants or their Design Agents requirement to explain why a deviation from the Councils Planning Policy should be allowed. Typical situations that could allow minimal distances for a house extension boundary could include offset siting of the neighbouring properties or perhaps the house extension adjoins an open field or the bottom of another neighbours garden.

It is also very useful to maintain a good gap for the house extension boundary for access into the rear garden from the front for example for bins and maintenance. Even if you are allowed to build your house extension right up to the boundary, it is always wise to retain some form of gap to ensure none of the new extension works encroaches over the boundary line such as the foundations, eaves or roof verges.