Brent planning: 85.5% of householder cases approved, one large rear extension in three refused at prior approval

Why does Brent approve most householder cases but refuse many large rear extensions at prior approval?

Brent refused 134 of its 924 householder applications. Its 85.5% approval rate ranks 17th of the 32 boroughs with a published figure, and it is 4.8 points below England's 90.3%. On speed it does better: 673 of 690 standard decisions came within eight weeks, 97.5%, 4th of 32. A further 234 decisions ran under a planning performance agreement or an agreed extension of time, 225 of them in time, and the eight-week measure leaves those out.

Large home extensions under prior approval tell a different story. The national rules let a single-storey rear extension reach 6m on an attached house or 8m on a detached one, if the house is not on article 2(3) land (conservation areas are article 2(3) land) and the council gives prior approval. Brent decided 243 and refused 79. The statistics give no reasons, so the figure is a warning that a 6m extension is not a formality here, not a verdict on any one scheme. Prior approval can also be refused for breaching the Class A limits or for too little information (GPDO A.4(3)).

The council's own Residential Extensions and Alterations SPD, paragraph 1.1.5, says that where prior approval is required the council will seek to apply the SPD's guidance. Its single-storey rear extension section sets depths of 6m (attached) and 8m (detached) but also says depth must not be more than half the length of the garden, and that there must be acceptable daylight to habitable rooms and no significant harm to neighbours' outlook or amenity space (paragraphs 3.1.4, 3.1.11 and 3.1.12). We have not seen the refusal notices, so we cannot say which of these tests decided the 79 refusals.

On appeal, the Planning Inspectorate allowed 71 of 186 householder appeals against Brent over five years, 38.2%, 15th of 32 and 3.8 points above the national rate of 34.4%.

How many conservation areas does Brent have?

The council's heritage page says there are 22 conservation areas. It lists 23 headings, but one, Sudbury Cottages, is marked de-designated on 28 May 2024, leaving 22, including Kensal Rise, designated that day. The Local Plan (2022) also says 22, about 7% of the borough, before those changes. The national register in our dataset (15 August 2026) records 23, which we have not reconciled. The headings are Barn Hill, Brondesbury, Buck Lane, Harlesden, Homestead Park, Kensal Green, Kensal Rise, Kilburn, Lawns Court, Mapesbury, Mount Stewart, Neasden Village, North Kilburn, Northwick Circle, Paddington Cemetery, Queens Park, Roe Green Village, South Kilburn, St. Andrews, Sudbury Cottages, Sudbury Court, Wembley High Street and Willesden Green. Treat the council's list as the one that decides and confirm your address with the conservation team.

The page gives designation dates. Roe Green Village was designated in November 1968, Buck Lane and South Kilburn in February 1979, Mapesbury in December 1982, Queens Park in July 1986 (extended July 1995) and Willesden Green in January 1993. The page says Brent has one Grade I building, nine Grade II* and around 200 Grade II. Design guides are linked for Barn Hill, Mapesbury, Mount Stewart, North Kilburn, Queens Park, Roe Green Village and Sudbury Court. For the other areas the page lists none.

Status changes what is allowed. A dormer is an enlargement of the roof, and Class B of Part 1 of the General Permitted Development Order does not apply on article 2(3) land, which includes conservation areas. The council's own page says conservation areas have fewer permitted development rights, and its validation list asks for a heritage statement for householder applications in them. Our conservation areas and Article 4 guide explains the national rules, and the neighbouring Camden borough page covers the other side of the Kilburn boundary.

Does a Brent basement need planning permission?

Often. Policy BD3 of the Local Plan says a basement under an existing property must be ancillary to the dwelling above if habitable, be no wider than the original building, extend no further than the existing front elevation, go no further than 3m to the rear and one storey down (4m floor to ceiling for a detached house, 3m otherwise), and be protected from sewer flooding by a pumped device. Front lightwells must be no more than the smaller of 800mm or half the garden length.

The Basement SPD, adopted in June 2017, adds that a basement in a conservation area or under a flat needs planning permission and that applicants are strongly encouraged to use pre-application advice. It also says parts of the borough are affected by flooding from the River Brent and its tributaries. The SPD pre-dates the 2022 Local Plan and cites older policy numbers such as DMP9a, so use BD3 for the current policy wording. The householder validation list asks for a basement impact assessment with every application that includes a basement.

Our basement conversion plans service covers the drawings side. A party wall notice under the Party Wall etc. Act 1996 is separate from planning: the Basement SPD covers it under other consents (section 1.3), and the Extensions SPD repeats it at 1.6.

Which parts of Brent are growth areas, and does that matter for a home extension?

The Local Plan contains growth area policies for Wembley, Neasden Stations, Staples Corner, Burnt Oak and Colindale, Northwick Park, Church End, South Kilburn and Alperton. The part of the borough administered by the Old Oak and Park Royal Development Corporation is excluded from the area of the council's emerging Local Plan. The council has adopted masterplan SPDs for Staples Corner (12 November 2024), Neasden Stations, Church End and South Kilburn.

For a householder the practical point is flats. The Extensions SPD says maisonettes, flats and houses converted into flats normally need planning permission for most external changes, and the permitted development rules for house extensions apply to houses only. A flat or maisonette project is a full planning application, not a householder one, and the SPD's 10% biodiversity net gain note applies to flats where the work affects more than 25 square metres of land.

The SPD also says that in growth areas, intensification corridors, town centres and areas with a public transport accessibility level of 3 or more, private external amenity space is desirable, and that any such space should be designed to reduce overlooking of neighbouring windows and gardens, for example with screening.

What should you check first for Brent planning?

Check the address against the council's list of conservation areas and its Article 4 page, then the Residential Extensions and Alterations SPD, then the Local Plan policy that applies to your project: BD3 for a basement, BH12 for an outbuilding, BHC1 where a heritage asset is involved. Those three steps go a long way to deciding whether a rear extension or loft can use permitted development, needs prior approval, or needs an application read against the SPD's garden-length, 45 degree and set-back tests.

Flood risk is the other early check. The SPD says that if an extension or outbuilding falls in an area of surface water flooding shown on the Local Plan policies map, the application will have to be amended, usually with a flood risk assessment. The council's page on special considerations says properties in flood risk areas may need additional drainage or flood risk assessments, and points to the interactive planning map for conservation areas, Article 4 directions and flood zones.