A typical brief
The owners of a 1930s semi in Finchley, Barnet, have an attached garage with a leaking flat roof that is used for storage. They want to convert it into a utility room and WC and extend behind it to the rear wall to widen the kitchen.
Constraints and planning context
Under Class A permitted development a single-storey side extension may be no wider than half the width of the original house and no higher than 4 m. The original house is 6.4 m wide, so the limit is 3.2 m; the extension needed here is 3.4 m wide to line through with the existing garage. Those 200 mm take it outside permitted development, and a Lawful Development Certificate would be refused on width alone. The route is therefore a householder planning application, where Barnet’s design guidance asks side extensions to be set back from the front and to have a subordinate roof.
How we would design it
The converted garage keeps its set-back front, with the garage door replaced by a window in matching brick. The new extension continues the 3.4 m width to the rear wall under a single pitched roof that matches the tile and pitch of the main house, with the eaves held below the first-floor windows. Inside, the kitchen gains 1.9 m of width, with a utility room and WC at the front.
Likely planning route
A householder planning application decided within the statutory 8 weeks. A set-back side extension with a matching pitched roof is what Barnet’s guidance asks for, so approval with conditions on materials is the normal outcome. The application fee is £528 (verify before applying). The Building Regulations package follows, covering the garage floor, insulation and roof structure.
Documentation we would prepare
- Measured survey and existing drawings
- Written PD assessment explaining why the width needs planning permission
- Proposed plans, elevations and roof plan for planning
- Householder planning application and submission
- Building Regulations drawings and specification
Read more about our house extensions, householder planning applications and Building Regulations drawings, see how we work in Barnet, or get an instant estimate.
