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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 6,230 real decisions tell us about rear extension outcomes in Lambeth.

6,230 real decisions·January 2020 to September 2026·Updated September 2026
82.2%
Approval Rate
6,230
Decisions
5,119
Approved
1,111
Refused
82.2% approved. But 1,111 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.

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 Conversion2,921
89.2%
Conservatory362
87.6%
Garage / Parking4,637
87.3%
Extension (General)1,561
85.3%
Side Extension2,272
85.2%
New Build2,167
85.0%
Basement3,532
84.6%
Outbuilding1,009
84.2%
Wraparound Extension398
83.2%
Rear Extension6,230
82.2%
Dormer3,232
81.2%
Change of Use (Residential)2,630
78.9%
Annex64
78.1%
Loft Conversion3,623
78.0%
Hip-to-Gable Conversion475
77.3%
Front Extension72
76.4%
HMO283
63.6%
See how this applies to your postcode →

What the data tells us

1
82.2% of rear extension applications in Lambeth get approved. That means 1,111 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

1,111 rear extension applications in Lambeth have been refused since 2020. Many of those homeowners had already paid for drawings and application fees. A free, property-specific report shows you what gets approved — and what gets refused — near your property.

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Free · Property report emailed in minutes · Based on 3,840,000+ real decisions

More Lambeth planning data

Nearby councils rear extension data

Methodology: Based on 6,230 planning decisions classified as rear extensions in Lambeth, January 2020 to September 2026. 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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