Architects in HA3

Kenton, Harrow Weald, Wealdstone, Belmont and part of Queensbury. Interwar semi-detached houses, typically extended at the side and rear, with lofts.

RIBA Chartered Practice · ARB-registered architects · Extensions, lofts and planning drawings

Planning authority

Which council decides in HA3?

HA3 is split between 2 councils, so the council that decides your application depends on your street. 1,264 postcodes, 5 miles from our studio.

Council	Share of HA3 postcodes
Harrow	77% (975)
Brent	23% (289)

Sector	Postcodes	Council
HA3 0	215	Brent
HA3 3	24	Harrow
HA3 5	172	Harrow
HA3 6	212	Harrow
HA3 7	221	Harrow
HA3 8	204	Harrow
HA3 9	216	Harrow (mostly; some streets in another council)

Postcode checker

Type any postcode in the 33 London boroughs we cover. We'll tell you which council handles planning there and show you the local planning points.

Local planning points

The Residential Design Guide SPD (2010) sets no fixed depth for single-storey rear extensions that need permission. Extra depth is expected to be set in from the side boundary by twice that depth.
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Two-storey rear extensions must meet the 45-degree code and are generally not possible on mid-terraced houses.
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The Harrow Local Plan 2021–2041 was adopted on 24 March 2026, replacing the 2012 Core Strategy and 2013 development management policies.
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Local planning points

Single-storey rear extensions are normally limited to 3m deep on terraced and semi-detached houses and 4m on detached houses, with more depth possible if set in from the boundary (Residential Extensions and Alterations SPD 2, 2018).
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Rear dormers outside conservation areas can be the full width of the original roof but must sit at least 0.3m below the ridge and 0.5m above the eaves.
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Basements should be no wider than the original house, extend no more than 3m beyond the rear and be one storey deep (Basement SPD, 2017).
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Local work