Rear extension drawings in Brent from £625
Kilburn, Willesden, Wembley and Kingsbury: Brent’s January 2025 guide sets numbers for depth, height and outriggers, and a limit tied to your garden length.
£625 £475 drawings + £150 survey (£625 total), no VAT to add
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The short answer
Brent’s Residential Extensions and Alterations SPD, adopted on 16 January 2025, says a single-storey rear extension could be up to 6 metres deep on a terraced or semi-detached home and 8 on a detached one, but never more than half the length of your garden. Two-storey extensions are capped at 3 metres, or 4 on a detached house, and a 45 degree line. Our fee is £475 drawings + £150 survey (£625 total), no VAT to add; the council’s fee is separate.
Rear extension drawings
from £625
- Drawings
- £475
- Measured survey
- £150
- Total you pay
- £625
- VAT
- None to add
- A measured survey of the back of the house, the full length of the garden and the neighbours’ windows
- A garden-length check, because Brent limits depth to half of it
- The 45 degree line drawn from the nearest habitable window next door if there is a second storey
- Outrigger and side-return limits applied where your Victorian house has them
- Existing and proposed drawings to Brent’s householder list, and the route that fits submitted for you
£475 drawings + £150 survey (£625 total). A starting fee: we confirm one fixed figure after checking your address. The council’s own fee, where there is one, is paid to the council.
Get my fixed feeHow a Brent rear extension runs
Garden and house check
We measure the garden length, work out whether you are attached, detached or have an outrigger.
Survey
We survey the back, the garden and the neighbours’ windows and extensions.
Design
You choose depth and roof, and we set the height at the boundary against the SPD.
Draw and submit
We prepare the pack to Brent’s list and submit it, then answer the case officer.
Brent’s numbers, and the half-garden limit
Section 3.1 of the SPD is unusually specific. For attached homes, single-storey rear extensions could be up to 6 metres deep from the original rear wall, and for detached homes up to 8. Notwithstanding that, the depth must not be more than half the length of your garden, and the garden you keep has to meet the amenity standards in Local Plan policy BH13.
Height depends on depth. An extension up to 3 metres (attached) or 4 metres (detached) could be up to 4 metres high with an eaves height of no more than 3 metres. Deeper than that, it could still reach 4 metres high, but the eaves along the neighbour boundary must be no more than 2.5 metres. For example, a 5 metre kitchen on a terrace in Kilburn needs a 2.5 metre boundary eaves and a garden at least 10 metres long.
Two storeys, outriggers and side returns
Two-storey rear extensions are held much tighter: no more than 3 metres from the original rear wall for attached homes and 4 for detached, and not beyond a 45 degree line taken from the middle of the nearest habitable-room window on a neighbour’s original rear wall. Kitchens count as habitable, bathrooms do not.
Many Brent Victorian houses have an outrigger. Section 3.5 says an extension to an outrigger must not extend more than 3 metres from the outrigger’s end wall, and be no more than 3.5 metres high next to it with eaves no more than 2.5 metres along the boundary. That sets how far a side-return infill can go.
Conservation areas, validation and CIL
Brent has 22 conservation areas. Its residential Article 4 directions were designed for the street side of houses, so rear extension rights usually remain, but we read the one that covers your road. A heritage statement is needed in a conservation area or under a direction.
The householder list asks for existing and proposed plans, elevations and sections at 1:50 or 1:100. Brent CIL is £357.14 a square metre in 2026, on 100 square metres or more of new floor space, so a typical extension is outside it. Mayoral CIL is in band 2.
Rear extensions in Brent in numbers
643 of 660
Householder decisions by Brent Council between July 2025 and June 2026 (prior approvals left out) that were made inside 8 weeks.
Source: MHCLG live table PS2, district planning application statistics, July 2025 to June 2026 (GOV.UK)
6 m / 8 m
Depth a single-storey rear extension could reach from the original rear wall under the SPD: attached homes 6 metres, detached homes 8.
Half the garden
The SPD says the depth of a single-storey rear extension must not be more than half the length of your garden.
2.5 m
Eaves height along the neighbour boundary where a single-storey extension is deeper than 3 metres (attached) or 4 metres (detached).
3 m / 4 m
Deepest two-storey rear extension from the original rear wall under the SPD: attached homes 3 metres, detached 4.
45°
Line from the middle of the nearest habitable-room window next door that a two-storey extension must not cross.
3 m
Furthest an extension to an outrigger may project from the outrigger’s end wall.
22
Conservation areas in Brent, with an interactive map showing which policies apply to an address.
Source: Listed buildings and conservation areas (Brent Council)
1:50 or 1:100
Normal scale of Brent’s elevations, floor plans, sections and roof plans.
Source: Validation list for applications for householder planning permission (Brent Council)
£357.14
Brent CIL per square metre for residential permissions granted in 2026, from a £200 rate set in 2013.
Source: Community Infrastructure Levy and Section 106 (Brent Council)
Questions about rear extensions in Brent
How deep can a rear extension be in Brent?
The 2025 SPD says up to 6 metres for attached homes and 8 for detached, but never more than half your garden length. A shorter garden means a shallower extension.
What is the garden rule?
Depth must not exceed half the length of the garden, and what is left must meet Local Plan policy BH13 amenity space standards.
Can I extend an outrigger?
Yes, by up to 3 metres from its end wall, no more than 3.5 metres high beside it and with eaves of no more than 2.5 metres on the boundary.
Does the 45 degree rule apply to a single-storey extension?
The SPD applies it to two-storey extensions. A single-storey one is judged on depth, height at the boundary and the half-garden limit.
See how far your Brent house can go
Send the address and a photo of the back. We reply with the route and a fixed fee, from £475 drawings + £150 survey (£625 total).