Architects in TW4

Hounslow West and the streets around Hounslow Heath. Interwar terraces and semis.

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

Planning authority

Which council decides in TW4?

TW4 is split between 2 councils, so the council that decides your application depends on your street. 429 postcodes, 9.5 miles from our studio.

Council	Share of TW4 postcodes
Hounslow	85% (363)
Richmond upon Thames	15% (66)

Sector	Postcodes	Council
TW4 5	166	Hounslow (mostly; some streets in another council)
TW4 6	102	Hounslow
TW4 7	161	Hounslow

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

Single-storey rear extensions are limited to 3.05m deep on terraced houses, 3.65m on semi-detached and 4.25m on detached houses (Residential Extension Guidelines, May 2024).
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Full-width box dormers are normally refused; dormers must be set in from the ridge, eaves and sides, by at least 1m on larger houses.
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A borough-wide Article 4 direction has required planning permission for small HMOs since 4 September 2023.
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Local planning points

A new Richmond upon Thames Local Plan (2024 to 2039) was adopted on 7 October 2025.
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Single-storey rear extensions are usually acceptable if they project no more than 3m on terraced houses, 3.5m on semi-detached houses and 4m on detached houses, as a starting point that depends on the site (House Extensions and External Alterations SPD, 2015). The SPD predates the 2025 Local Plan.
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Dormer windows and other roof extensions must not project above the ridgeline, and raising the ridge of the house is normally unacceptable (House Extensions and External Alterations SPD, 2015).
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Local work