Rear extension drawings in Lewisham from £625
Brockley, Blackheath, Catford and Sydenham: Lewisham’s 2019 extensions guide sets a 3 metre depth and a 2.5 metre limit on the boundary.
£625 £475 drawings + £150 survey (£625 total), no VAT to add
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The short answer
Lewisham’s Alterations and Extensions SPD, adopted in April 2019, says rear extensions should generally be no more than 3 metres deep for terraced or semi-detached houses, with no more than 3 metres height on the boundary at that length. Longer ones over 2.5 metres high on the boundary are unlikely to be supported, and no extension should take more than half the original garden depth. 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 original garden depth and the neighbours’ windows
- A depth, boundary height and half-garden check against the April 2019 SPD
- The test the SPD gives for extensions close to neighbouring windows, drawn on the plans
- A check of your address against Lewisham’s Article 4 directions, including Blackheath
- A scale bar showing 1 m and 10 m, 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 Lewisham rear extension runs
Garden depth check
We measure the original garden depth and work out the half-depth limit.
Survey
We measure the back, the boundary heights and the neighbours’ windows.
Design
You choose depth and roof, with boundary height and route written down.
Draw and submit
We prepare the pack to the checklist and submit it, then answer the case officer.
What section 4.2 sets
Section 4.2.3 says rear extensions should generally not be more than 3 metres deep for terraced or semi-detached properties, with deeper ones potentially acceptable for detached properties or large plots. Under no circumstances should an extension take up more than half the depth of the original rear garden or yard, to avoid overdevelopment.
Height on the boundary is tied to length. As a general rule, extensions up to 3 metres long should be no more than 3 metres high on the boundary, and extensions beyond that length that exceed 2.5 metres on the boundary are unlikely to be supported. A pitched roof ridge should sit visibly below the sill of any first-floor window, by at least two or three brick courses. For example, a 4 metre kitchen is workable only with a boundary wall at 2.5 metres or less.
Infills and wrap-arounds, Victorian-style
Many Lewisham houses have an outrigger, so section 4.5 covers infill and wrap-around extensions. It says their height depends on the scale of the outrigger, the garden width and the depth, and the same rule applies: up to 3 metres long, no more than 3 metres high; beyond that, over 2.5 metres on the boundary is unlikely to be supported. It recommends keeping a path of at least 1 metre beside an L-shaped extension.
Under Class A permitted development gives 3 or 4 metres, and 6 and 8 through prior approval, but Lewisham’s Article 4 directions, including four separate ones in Blackheath, control roofs and other works on single-dwelling houses where visible from public viewpoints. We check your road.
Validation and CIL
Lewisham’s July 2022 householder checklist asks for plans at 1:50 or 1:100 and a scale bar showing 1 metre and 10 metres on every drawing, and gives 21 days to supply missing information before the application is withdrawn.
Lewisham’s CIL was set in 2015 at £100 a square metre in zone 1 and £70 in zone 2, indexed since, and applies from 100 square metres of new floor space, so a typical extension is outside it. Mayoral CIL is in band 2.
Rear extensions in Lewisham in numbers
393 of 413
Householder decisions by Lewisham 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)
3 m
Depth rear extensions should generally not exceed for terraced or semi-detached properties.
Source: Alterations and Extensions SPD, adopted April 2019, sections 4.2 and 4.5 (Lewisham Council)
Half
No extension should take up more than half the depth of the original rear garden or yard.
Source: Alterations and Extensions SPD, adopted April 2019, sections 4.2 and 4.5 (Lewisham Council)
2.5 m
Boundary height above which an extension longer than 3 metres is unlikely to be supported.
Source: Alterations and Extensions SPD, adopted April 2019, sections 4.2 and 4.5 (Lewisham Council)
Apr 2019
Date Lewisham adopted its Alterations and Extensions SPD.
Source: Alterations and Extensions SPD, adopted April 2019, sections 4.2 and 4.5 (Lewisham Council)
1 m
Path the SPD recommends keeping beside an L-shaped single-storey rear and side extension.
Source: Alterations and Extensions SPD, adopted April 2019, sections 4.2 and 4.5 (Lewisham Council)
4
Separate Article 4 directions in Blackheath: Belmont, Collins Street, 52 Lee Terrace and Quentin Road.
Source: Article 4 directions in conservation areas (Lewisham Council)
1 m and 10 m
Lengths the scale bar on every plan and drawing must show.
Source: Validation checklist: householder application for planning permission, July 2022 (Lewisham Council)
21 days
Time Lewisham gives to supply missing information before an invalid application is withdrawn.
Source: Validation checklist: householder application for planning permission, July 2022 (Lewisham Council)
£100 and £70
Lewisham CIL per square metre for residential in zone 1 and zone 2 when it took effect on 1 April 2015.
Source: Community Infrastructure Levy Charging Schedule, taking effect 1 April 2015 (Lewisham Council)
Questions about rear extensions in Lewisham
How deep can I go in Lewisham?
Generally 3 metres for a terrace or semi. Detached houses and large plots may go further, but never beyond half the original garden depth.
What is the boundary height rule?
Up to 3 metres long, up to 3 metres high on the boundary. Longer than that and over 2.5 metres on the boundary, it is unlikely to be supported.
Does that apply to wrap-around extensions?
Yes. They are generally over 3 metres long, so the height on the boundary is the key consideration.
Do I pay CIL on a kitchen extension?
Not normally. It applies from 100 square metres of new floor space or a new dwelling.
See how far your Lewisham 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).