Data-backed planning intelligence · 2,500,000+ decisions analysed across England

Rear Extension Approval Rates in Lambeth

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 5,992 real decisions tell us about rear extension outcomes in Lambeth.

5,992 real decisions·January 2020 to present·Updated March 2026
82.2%
Approval Rate
5,992
Decisions
4,925
Approved
1,067
Refused
82.2% approved. But 1,067 refused since 2020. Each refusal cost the homeowner time and money on drawings and application fees. Understanding your local data before you apply is the difference between confidence and a costly gamble.

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Why rear extension approval rates matter

Rear extensions sit in the middle of the pack nationally. They're common enough that councils have clear precedent — but that cuts both ways. If your neighbours have been refused, that precedent works against you too.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1KNIGHT55
100.0%
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These are council averages. Your property is specific.

Two houses on the same street can get different outcomes.
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How rear extensions compare to other project types

Not all applications are treated equally. Here's how rear extensions stack up against other common projects in Lambeth.

TypeDecisionsRate
Flat Conversion2,891
89.5%
Garage / Parking4,482
87.4%
Conservatory343
87.2%
New Build2,101
85.6%
Extension (General)1,481
85.1%
Basement3,456
85.0%
Side Extension2,175
84.9%
Outbuilding939
83.3%
Wraparound Extension381
82.7%
Rear Extension5,992
82.2%
Dormer3,133
81.4%
Change of Use (Residential)2,548
79.0%
Loft Conversion3,494
78.2%
Front Extension71
77.5%
Hip-to-Gable Conversion461
76.8%
Annex61
75.4%
HMO256
66.4%
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What the data tells us

1
82.2% of rear extension applications in Lambeth get approved. That means 1,067 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
3
Council averages are starting points, not guarantees. The decisions that matter most are the comparable ones near your specific property — because planning officers look at precedent, character and the immediate context of your street.

Before you spend £5,000+ on architects and drawings

1,067 rear extension applications in Lambeth have been refused since 2020. Many of those homeowners had already paid for drawings and application fees. A £79 report shows you what gets approved — and what gets refused — near your property.

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More Lambeth planning data

Nearby councils rear extension data

Methodology: Based on 5,992 planning decisions classified as rear extensions in Lambeth, January 2020 to present. Classification uses keyword matching against proposal descriptions (matching generate_site_data.py rules). A single application may appear in multiple categories. Approval rate = approved / (approved + refused). Pending, withdrawn and invalid applications excluded. Data from Lambeth Council's public planning portal. Full methodology →
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