Rear extension drawings in Brentford, TW8
A rear extension in Brentford can often be built without a full planning application if it stays within 3 metres deep on a terraced or semi-detached house, or 4 metres on a detached one. DrawingsDirect draws the plans, elevations and sections for the route you choose, from £695 fixed fee.
Fixed fee from £495 drawings + £200 survey (£695 total) · all prices
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How deep can a rear extension go in Brentford?
Permitted development rights let a single-storey rear extension go 3 metres beyond the rear wall of the original house where it is not detached, and 4 metres on a detached house (GPDO 2015, Schedule 2, Part 1, Class A.1(f)(i)). Those depths are for houses: flats do not have this right, and an Article 4 direction can remove it.
Check which limit applies before you commit to a design, because a few hundred millimetres over the line turns a quick route into a full application. The permitted development entry in our glossary explains how the right works and where it stops.
What if you want to go deeper?
The larger home extension route allows 6 metres on a house that is not detached and 8 metres on a detached house, but only after prior approval from the council (GPDO 2015, Schedule 2, Part 1, Class A.1(g)). The council notifies your neighbours and they can object. The statutory fee for that prior approval, from 1 April 2026, is £249.
Hounslow, the borough that covers Brentford, determined 171 of these prior approvals in the eight quarters 2024 Q3 to 2026 Q2 and granted 31% of them (our analysis of MHCLG planning application statistics, table PS1). That figure counts the notifications where the council found prior approval was required. Our guide to prior approval for a larger home extension explains the process step by step.
For Hounslow as a whole, our analysis of the MHCLG Planning Data Platform conservation-area dataset (snapshot retrieved 14 Aug 2026) counts 43 conservation-area entries on the national register.
When a full householder application is the better route
Hounslow granted 79% of its householder decisions in the four quarters 2025 Q3 to 2026 Q2 (our analysis of MHCLG planning application statistics, table PS2). A conventional application lets you propose a depth or shape permitted development cannot reach, and the council weighs it against its policies.
The trade-off is time and a larger set of drawings. We can draw both versions of a scheme so you can compare. See the rear extension drawings service for what the package includes.
Conservation areas and Article 4 directions around TW8
For Hounslow as a whole, our analysis of the MHCLG Planning Data Platform conservation-area dataset (snapshot retrieved 14 Aug 2026) counts 43 conservation-area entries on the national register.
The conservation-area count says little about your road, and the national Article 4 dataset is incomplete, so do not read a clear result as proof. An Article 4 direction can switch off the permitted development right entirely. Read the Article 4 explainer and use Hounslow's conservation area map, or ask the council, to confirm your address.
What the fixed fee covers
DrawingsDirect's rear extension drawings start from £695, as a fixed fee. That covers the drawings for the route you choose; the council's own fee is separate. The official limits are published on legislation.gov.uk.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| 3 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(f)(i): single-storey rear extension max depth, house other than detached (source wording: 3 metres) | www.legislation.gov.uk |
| 4 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(f)(i): single-storey rear extension max depth, detached house (source wording: 4 metres) | www.legislation.gov.uk |
| 6 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(g): larger home extension (prior approval, A.4) max depth, house other than detached (source wording: 6 metres) | www.legislation.gov.uk |
| 8 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(g): larger home extension (prior approval, A.4) max depth, detached house (source wording: 8 metres) | www.legislation.gov.uk |
| £249 | Statutory fee from 1 April 2026: prior approval for a householder larger rear extension (GPDO Part 1 Class A) | assets.publishing.service.gov.uk |
| 171 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 31% | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 79% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 43 | Our analysis of MHCLG Planning Data Platform conservation-area and article-4-direction datasets (bulk snapshot retrieved 14 Aug 2026) | www.planning.data.gov.uk |
| £695 | DrawingsDirect starting fixed fee for rear extension drawings, from the published price list | drawingsdirect.co.uk |
Questions people ask
Do I need planning permission for a rear extension in Brentford?
What is the difference between a rear extension and a house extension?
Will my neighbours be told?
Photographs: David Howard (CC BY-SA 2.0).
