Loft conversions in Brent

Brent's roof guidance

Brent's 2025 Residential Extensions and Alterations SPD is more permissive on lofts than the guidance in several neighbouring boroughs. Outside conservation areas, it says:

• rear dormers could be up to the full width of the original roof, set at least 0.2 metres up from the eaves and no higher than the ridge;
• L-shaped dormers over an outrigger or two-storey rear extension are generally acceptable, but should cover no more than half of its depth;
• hipped roofs could be converted to gables, provided the result suits the street and any side extensions;
• front dormers are only acceptable where they are already a common feature of the street, and side dormers need obscure glazing up to 1.7 metres.

Permitted development

Many lofts can be converted without an application. The national limits allow up to 40 cubic metres of extra roof space on a terraced house and 50 cubic metres on a semi-detached or detached house, with matching materials, no balconies, obscure-glazed side windows and the enlargement set back about 20 centimetres from the eaves. Roof enlargements are not permitted development in conservation areas, and Brent's residential conservation areas also have Article 4 directions, so expect a planning application there.

Whichever route applies, the conversion still needs Building Regulations approval for the structure, the escape route and the insulation, and party wall notices where steels bear on a party wall.