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Rear Extension Approval Rates in Merton

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 5,819 real decisions tell us about rear extension outcomes in Merton.

5,819 real decisions·January 2020 to August 2026·Updated August 2026
81.9%
Approval Rate
5,819
Decisions
4,764
Approved
1,055
Refused
81.9% approved. But 1,055 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.
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 Merton.

TypeDecisionsRate
Conservatory303
92.7%
Basement590
91.4%
Loft Conversion3,934
90.0%
Wraparound Extension481
88.8%
Dormer2,452
88.7%
Garage / Parking2,175
88.6%
New Build1,249
87.8%
Extension (General)937
87.2%
Hip-to-Gable Conversion1,177
86.9%
Side Extension1,980
85.2%
Change of Use (Residential)1,169
83.7%
Outbuilding1,050
83.1%
Flat Conversion880
83.1%
Rear Extension5,819
81.9%
Annex106
79.2%
Front Extension234
79.1%
HMO180
56.1%
See how this applies to your postcode →

What the data tells us

1
81.9% of rear extension applications in Merton get approved. That means 1,055 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

1,055 rear extension applications in Merton 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 3,820,000+ real decisions

More Merton planning data

Nearby councils rear extension data

Methodology: Based on 5,819 planning decisions classified as rear extensions in Merton, January 2020 to August 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 Merton Council's public planning portal. Full methodology →
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