Rear extension drawings in Lambeth from £625
Brixton, Clapham, Stockwell and Streatham terraces: Lambeth judges a back extension by the rear return it grows from, not by a metre count.
£625 £475 drawings + £150 survey (£625 total), no VAT to add
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The short answer
Lambeth gives no depth for a rear extension. Its Design Guide, adopted in August 2023, judges by form: a rear return should stay subordinate, enlarging one to full width will generally be resisted, and single-storey infills beside it are potentially acceptable if mostly glazed. A closet return is generally no deeper than it is wide. 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 rear return, the side space beside it and the neighbours’ windows
- A check that your design reads as an infill, end or wrap-around extension in the way the Design Guide accepts
- A check of your address against Lambeth’s 62 conservation areas and nine Article 4 directions
- Elevations that show the windows and doors of the adjoining buildings, with a linear scale bar, as the council asks
- The route that fits submitted for you, and answers to the case officer
£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 Lambeth rear extension runs
Read the back
We identify whether you have a rear return, a closet return or a flat back, and what your neighbours have done.
Survey
We measure the return, the side space and the neighbours’ windows onto it.
Design
You choose infill, end extension or wrap-around, with the route and risk of each written down.
Draw and submit
We prepare the pack to the December 2024 information requirements and submit it.
What the Lambeth Design Guide accepts at the back
Part 4 of the Lambeth Design Guide starts from the shape of the house. Rear returns are the narrow wings on mid-19th-century terraces; the guide says they are never full width, so the rear wall keeps its windows and doors. Enlarging a return to make it full-width will generally be resisted, and lengthening one may be possible if roof forms and materials match.
Single-storey infill extensions, which fill the side space beside the return, end extensions and wrap-arounds are potentially acceptable so long as subordination is achieved and there is no harm to amenity. To keep the original return dominant, infills should be mostly glazed. Wrap-arounds on houses with closet returns will generally be resisted because of the different internal floor level.
For example, a glazed side infill on a Brixton terrace is the easy case; a full-width brick box that swallows the return is the hard one. We draw the first and say plainly when a brief is heading towards the second.
Closet returns, full-width boxes and conservation areas
Where a house has a closet return, the guide says it is generally no deeper than it is wide, and demolishing one will generally be resisted. Full-width rear extensions need a positive response to the host building, and are unlikely to be acceptable on statutory listed buildings. Rooflights or lanterns are suggested to keep daylight in the rear room.
Lambeth has 62 conservation areas, covering about 30% of the borough, with Article 4 directions in places such as Albert Square, Hyde Farm, Leigham Court Estate and Stockwell Park. Class A permits 3 or 4 metres, or 6 and 8 through prior approval, but in a conservation area it does not apply.
What Lambeth asks for, and CIL
The Local Information Requirements issued in December 2024 ask for elevations showing where the windows and doors of the adjoining buildings sit, and a linear scale bar on every plan. A heritage statement is needed in a conservation area. Lambeth tells householders to expect a decision within 8 weeks.
Lambeth has charged its own CIL since 1 January 2022, from £500 a square metre in Zone A to £200 in Zone D before indexation, on a dwelling or 100 square metres or more of new build. A typical rear extension is outside it. Mayoral CIL is in band 2.
Rear extensions in Lambeth in numbers
333 of 354
Householder decisions by Lambeth 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)
Full width
The Design Guide says enlarging a rear return to make it full-width will generally be resisted.
Not deeper than wide
The Design Guide says closet returns are generally no deeper than they are wide.
3 m / 4 m
Deepest single-storey extension permitted development allows; 6 and 8 metres through prior approval.
Source: GPDO 2015, Schedule 2, Part 1, Class A: enlargement of a dwellinghouse (legislation.gov.uk)
62
Conservation areas in Lambeth, covering about 30% of the borough.
9
Named conservation area directions in Lambeth, from Albert Square to Vauxhall, removing permitted development rights for external alterations.
Adjoining windows
Lambeth’s information requirements ask for elevations showing the windows and doors of neighbouring buildings.
Source: Local Information Requirements 2024 (Lambeth Council)
8 weeks
The householder decision period Lambeth tells applicants to expect.
Source: Apply for householder planning permission (Lambeth Council)
£500 to £200
Lambeth CIL per square metre for residential across Zones A to D from 1 January 2022, before indexation.
£72.73
Mayoral CIL per square metre for permissions granted in 2026 in Lambeth, which is in band 2 (£60 when set in 2019). It applies only where CIL is due at all.
Source: Mayoral CIL: Annual CIL Rate Summary 2026 (London.gov.uk)
Questions about rear extensions in Lambeth
How deep can I extend in Lambeth?
There is no council figure. Permitted development gives 3 or 4 metres outside conservation areas; beyond that, form, subordination and neighbours’ amenity decide.
Can I fill in the side space beside my rear return?
Often yes. The Design Guide says single-storey infills are potentially acceptable if subordinate, and they should be mostly glazed so the return stays dominant.
Can I build a full-width extension?
Enlarging a rear return to full width will generally be resisted. A full-width box on a flat-backed house is judged on its response to the building and its roof.
Why do my neighbours’ windows appear on my elevations?
Lambeth’s information requirements ask for it, so the case officer can judge overlooking at a glance. We measure them during the survey.
See how far your Lambeth 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).