House Extension Drawings in Hounslow

Where in Hounslow does a house extension actually get determined?

Every Hounslow postcode district we draw in, the stock that dominates it and the authority that validates a house extension there. Hounslow fees below are the statutory England rates for 2026, not house extension estimates.

How does a house extension differ street by street across Hounslow?

Roof pitch, wall build-up and plot depth change every few Hounslow streets, and each one changes what a house extension can achieve at that address.

• Chiswick (W4) — a house extension in Chiswick starts from edwardian villas, victorian terraces, and Chiswick reads as Edwardian villas, conservation. The side-return infill is the classic move on these Victorian terraces — 3 m of permitted development depth plus the width of the original side passage in W4. Hounslow Council assesses Chiswick house extensions against its own Chiswick character guidance, and the location plan we draw for Chiswick references Chiswick House.
• Brentford (TW8) — a house extension in Brentford starts from georgian fragments, victorian terraces, new-build, and Brentford reads as Georgian fragments, riverside new-build. Georgian rear elevations here are usually the listed or locally listed face of the building in TW8. Hounslow Council assesses Brentford house extensions against its own Brentford character guidance, and the location plan we draw for Brentford references Kew Bridge.
• Isleworth (TW7) — a house extension in Isleworth starts from georgian and victorian terraces, and Isleworth reads as Georgian and Victorian terraces. Georgian rear elevations here are usually the listed or locally listed face of the building in TW7. Hounslow Council assesses Isleworth house extensions against its own Isleworth character guidance, and the location plan we draw for Isleworth references Old Isleworth.
• Hounslow (TW3) — house extension work in Hounslow means 1930s semi-detached, post-war flats. Hounslow is 1930s semi-detached, post-war flats. 1930s semis here have the deepest rear gardens in the area throughout TW3. Hounslow Council decides the Hounslow application, and Hounslow Central anchors the Hounslow location plan.
• Feltham (TW13) — 1930s semi-detached, post-war estates defines Feltham, where 1930s semi-detached, post-war estates set what a house extension can do. 1930s semis here have the deepest rear gardens in the area across TW13. Any Feltham house extension is validated by Hounslow Council, with Feltham station the usual Feltham reference point on the site plan.
• Hanworth (TW13) — a house extension in Hanworth starts from 1930s semi-detached, and Hanworth reads as 1930s semi-detached. 1930s semis here have the deepest rear gardens in the area in TW13. Hounslow Council assesses Hanworth house extensions against its own Hanworth character guidance, and the location plan we draw for Hanworth references Hanworth Park.
• Turnham Green (W4) — house extension work in Turnham Green means edwardian villas. Turnham Green is Edwardian villas, conservation. Edwardian plots here are wider throughout W4. Hounslow Council decides the Turnham Green application, and Turnham Green anchors the Turnham Green location plan.

Does Hounslow planning policy restrict a house extension?

Hounslow conservation designations: there are 30 across Hounslow Council, Bedford Park, Old Isleworth, Brentford among them. Designation costs a Hounslow owner the permitted-development route: a house extension then needs a £548 householder application over 8 weeks, in place of the £249 prior approval route that takes 6 weeks. Bedford Park is the Hounslow designation that most often changes a house extension design.

No blanket Article 4 over Hounslow: Hounslow Council has not withdrawn permitted development across Hounslow, so a house extension outside a Hounslow conservation area usually keeps it. The £274 Lawful Development Certificate is still the document a W4 owner wants on file.

Hounslow housing stock: Edwardian villas in Chiswick and Turnham Green; Georgian in Isleworth; 1930s semi-detached in Hounslow and Feltham; riverside new-build in Brentford. Chiswick is one of west London's most conservation-controlled areas; outer Hounslow is permissive suburban. Read that before choosing a house extension route in Hounslow — construction, not postcode, sets what is achievable. Hounslow Council charges £548 for a householder application and has 8 weeks to determine it.

Who decides a house extension on the edge of Hounslow?

• Hillingdon — adjoining Hounslow, with 29 conservation areas centred on HA4. A house extension on the far side of the Hounslow line is determined by Hillingdon Council, so the Hounslow quote for house extensions is checked against Hillingdon guidance before it is issued.
• Ealing — adjoining Hounslow, with 30 conservation areas centred on W3. A house extension on the far side of the Hounslow line is determined by Ealing Council, so the Hounslow quote for house extensions is checked against Ealing guidance before it is issued.
• Hammersmith and Fulham — adjoining Hounslow, with 45 conservation areas centred on W6. A house extension on the far side of the Hounslow line is determined by Hammersmith & Fulham Council, so the Hounslow quote for house extensions is checked against Hammersmith and Fulham guidance before it is issued.
• Richmond upon Thames — the Richmond upon Thames boundary runs against Hounslow, so a house extension a street from Hounslow is decided by Richmond Council instead. Richmond upon Thames runs 72 conservation areas across SW13 and its neighbours, which is why house extensions priced for Hounslow are re-checked against Richmond upon Thames policy whenever the Hounslow address sits on that edge.

Sources for this Hounslow house extension page: borough policies maps and conservation-area registers (2025–26), Royal Mail postcode district boundaries, the Town and Country Planning (Fees for Applications) (England) Regulations, the Town and Country Planning (General Permitted Development) (England) Order 2015 as amended, and the Party Wall etc. Act 1996.