London Borough of Lambeth

Adopted Documents We Assess Against

Development plan: Lambeth Local Plan 2021

Documents are re-checked against the council's own website weekly. A detected change flags "Policy Update Available" for human review — live assessment standards are never replaced automatically.

London Borough of Lambeth standards at a glance

5 numeric standards taken from London Borough of Lambeth's own adopted documents, each shown with the paragraph it comes from. Figures differ between councils — these are this one's.

Side extension form

at least 1m

Lambeth want at least a metre between a side extension and the boundary at first floor and above - and they say plainly that on some streets they will want considerably more than a metre. Design Guide SPD Part 4 para 4.68

Roof form

up to 70°

The council runs a rear mansard lower pitch at 70 degrees. Lambeth Design Guide (provisional citation)

at least 2.1

The council requires a rear mansard to keep 2.1m of internal headroom below the existing ridge. Lambeth Design Guide (provisional citation)

at least 1.1

The council requires an inset roof terrace to retain the roof slope with a 1.1m balustrade. Lambeth Design Guide (provisional citation)

Design character

up to 30%

Lambeth are stricter than most: 70 per cent of the back garden has to stay free of the basement and at its original level, so no more than 30 per cent can be built under. Lambeth Local Plan Policy Q27 (Basement development)

Standards are what the council normally expects, not a guarantee. A scheme outside them can still be approved on its merits, and one inside them can still be refused for another reason.

Authored Policy Library

8 local policy checks, each citation-locked to the adopted document. National policy (NPPF, national space and daylight standards) applies alongside these.

Lambeth Local Plan 2021

• Lambeth Local Plan Policy Q11 — Design character Lambeth expects extensions to sit clearly below and behind the main building and to take their cues from it. Their Design Guide sets out what "subordinate" means in practice - worth reading before you finalise the drawings.
• Lambeth Local Plan 2021 (residential amenity policies) — Amenity neighbouring (provisional citation) Lambeth will look at the effect on your neighbours' light, outlook and privacy. Show the relationship to their windows on your drawings.
• Lambeth Design Guide — Roof form (3 checks) (provisional citation) The council runs a rear mansard lower pitch at 70 degrees. The council requires a rear mansard to keep 2.1m of internal headroom below the existing ridge. The council requires an inset roof terrace to retain the roof slope with a 1.1m balustrade.
• Lambeth Local Plan Policy Q27 (Basement development) — Design character Lambeth are stricter than most: 70 per cent of the back garden has to stay free of the basement and at its original level, so no more than 30 per cent can be built under.

Lambeth Design Guide SPD Part 4: Building Alterations, Extensions and Retrofit (August 2023)

• Design Guide SPD Part 4 para 4.68 — Side extension form Lambeth want at least a metre between a side extension and the boundary at first floor and above - and they say plainly that on some streets they will want considerably more than a metre.
• Design Guide SPD Part 4 paras 4.91 to 4.103 — Roof form Lambeth are specific about roofs rather than about extension depth. A mansard runs at 70 degrees, stops at 2.3 metres, and needs 2.1 metres of headroom under the existing ridge. Dormer heads need 2.1 metres too.