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Rear Extension Approval Rates in Lewisham

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 4,713 real decisions tell us about rear extension outcomes in Lewisham.

4,713 real decisions·January 2020 to present·Updated June 2026
75.5%
Approval Rate
4,713
Decisions
3,558
Approved
1,155
Refused
75.5% approved. But 1,155 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.

Ward gap in Lewisham: Forest Hill approves 100.0% of rear extension applications while Crofton Park sits at 80.0%. That 20.0% gap means your postcode is one of the strongest indicators of outcome.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1Forest Hill55
100.0%
2Lee Green77
100.0%
3Crofton Park54
80.0%
See how this applies to your postcode →

These are council averages. Your property is specific.

A rear extension has a 100.0% approval rate in Forest Hill but just 80.0% in Crofton Park.
Check your postcode to see what actually happens near your address.

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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 Lewisham.

TypeDecisionsRate
New Build303
88.8%
Wraparound Extension449
84.6%
Extension (General)2,724
84.1%
Flat Conversion2,760
83.7%
Conservatory363
83.2%
Garage / Parking3,651
83.1%
Outbuilding837
82.8%
Basement1,243
82.5%
Hip-to-Gable Conversion892
82.0%
Dormer2,062
81.5%
Loft Conversion2,647
79.3%
Change of Use (Residential)2,046
78.5%
Side Extension1,181
76.0%
Rear Extension4,713
75.5%
Annex80
68.8%
HMO470
61.3%
Front Extension61
60.7%
See how this applies to your postcode →

What the data tells us

1
75.5% of rear extension applications in Lewisham get approved. That means 1,155 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
2
Your ward matters more than you think. The 20.0% gap between Forest Hill (100.0%) and Crofton Park (80.0%) means your postcode is one of the strongest indicators of outcome.
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

1,155 rear extension applications in Lewisham 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 3,290,000+ real decisions

More Lewisham planning data

Nearby councils rear extension data

Methodology: Based on 4,713 planning decisions classified as rear extensions in Lewisham, 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 Lewisham Council's public planning portal. Full methodology →
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