London Borough of Lewisham

Adopted Documents We Assess Against

Development plan: Lewisham Local Plan 2020-2040 (adopted 16 July 2025)

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 Lewisham standards at a glance

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

Rear extension depth

up to 3m

Lewisham work to 3 metres deep on a terrace or semi - but the harder rule is that the extension must never take more than half the depth of your original garden, so on a short garden that is what will decide it. Alterations and Extensions SPD 4.2.3

Side extension form

at least 0.15m

A Lewisham side extension needs at least 150mm set back from the front wall, and single storey should be no more than half the width of the house. Two storeys is stricter: a metre off the boundary and a metre back from the front, or two metres back if you build right up to the boundary. Alterations and Extensions SPD 4.4.4 and 4.4.6

Roof form

at least 0.3m

Keep the dormer at least 0.3m in from the side of the roof. Alterations and Extensions SPD 5.7.2 and 5.8.2

at least 0.3m

Keep the top of the dormer at least 0.3m below the ridge. Alterations and Extensions SPD 5.7.2 and 5.8.2

at least 0.3m

Keep the bottom of the dormer at least 0.3m above the eaves. Alterations and Extensions SPD 5.7.2 and 5.8.2

Design character

up to 3

The council limits a basement to 3m beyond the original rear wall, OR a quarter of the original garden length, whichever is the LESS - so on a short garden the quarter-length test binds first and this 3m check is the looser of the two. Alterations and Extensions SPD

at least 2.4

The council requires a minimum 2.4m floor-to-ceiling height. Alterations and Extensions SPD

at least 1

The council requires at least 1m depth of soil retained above a basement running under the garden. Alterations and Extensions SPD

up to 1.5

The council limits a front lightwell to 1.5m from the original front wall. Alterations and Extensions SPD

Amenity space

at least 50%

If Lewisham accept parking in your front garden, half of that garden still has to stay planted rather than paved. Lewisham Alterations and Extensions SPD, section 6

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

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

Lewisham Local Plan 2020-2040

• Lewisham Local Plan 2020-2040 (design and local character policies) — Design character (provisional citation) Lewisham replaced its old planning policies in July 2025. Design is judged on how well the proposal responds to the host building and street - and be careful with older guidance you find online, as the policy numbers have changed.
• Lewisham Local Plan 2020-2040 (residential amenity policies) — Amenity neighbouring (provisional citation) Lewisham will look at the effect on your neighbours' light, outlook and privacy. Show the relationship to their windows on your drawings.

Lewisham Alterations and Extensions SPD (April 2019)

• Alterations and Extensions SPD 4.2.3 — Rear extension depth Lewisham work to 3 metres deep on a terrace or semi - but the harder rule is that the extension must never take more than half the depth of your original garden, so on a short garden that is what will decide it.
• Alterations and Extensions SPD 4.4.4 and 4.4.6 — Side extension form A Lewisham side extension needs at least 150mm set back from the front wall, and single storey should be no more than half the width of the house. Two storeys is stricter: a metre off the boundary and a metre back from the front, or two metres back if you build right up to the boundary.
• Alterations and Extensions SPD 5.7.2 and 5.8.2 — Roof form (4 checks) Lewisham want 300mm clear on every side of a rear dormer - off each party wall, below the ridge, in from the hip and above the eaves. In a conservation area the roof extension also has to stay under two-thirds of the original roof width. Keep the dormer at least 0.3m in from the side of the roof. Keep the top of the dormer at least 0.3m below the ridge. Keep the bottom of the dormer at least 0.3m above the eaves.
• Alterations and Extensions SPD 4.8.8 to 4.8.20 — Design character A Lewisham basement can go 3 metres past the original rear wall or a quarter of the garden length, whichever is smaller - so a short garden is the binding constraint. You also need 2.4 metres of headroom and a metre of soil above any part under the garden.
• Alterations and Extensions SPD — Design character (4 checks) The council limits a basement to 3m beyond the original rear wall, OR a quarter of the original garden length, whichever is the LESS - so on a short garden the quarter-length test binds first and this 3m check is the looser of the two. The council requires a minimum 2.4m floor-to-ceiling height. The council requires at least 1m depth of soil retained above a basement running under the garden. The council limits a front lightwell to 1.5m from the original front wall.
• Lewisham Alterations and Extensions SPD, section 6 — Amenity space If Lewisham accept parking in your front garden, half of that garden still has to stay planted rather than paved.