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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 5,617 real decisions tell us about rear extension outcomes in Merton.

5,617 real decisions·January 2020 to present·Updated March 2026
81.5%
Approval Rate
5,617
Decisions
4,576
Approved
1,041
Refused
81.5% approved. But 1,041 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 Merton: Lower Morden approves 100.0% of rear extension applications while Raynes Park sits at 83.3%. That 16.7% gap means your postcode is one of the strongest indicators of outcome.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1Lower Morden66
100.0%
2Cannon Hill66
100.0%
3West Barnes76
85.7%
4Wimbledon Town and Dundonald76
85.7%
5Raynes Park65
83.3%
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 Lower Morden but just 83.3% in Raynes 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 Merton.

TypeDecisionsRate
Conservatory288
93.1%
Basement573
91.3%
Loft Conversion3,839
89.9%
Garage / Parking2,106
88.7%
Wraparound Extension470
88.5%
Dormer2,346
88.3%
New Build1,232
87.7%
Hip-to-Gable Conversion1,151
86.8%
Extension (General)874
86.6%
Side Extension1,898
84.9%
Change of Use (Residential)1,149
83.9%
Outbuilding1,002
82.8%
Flat Conversion873
82.8%
Rear Extension5,617
81.5%
Annex101
79.2%
Front Extension229
78.2%
HMO174
55.7%
See how this applies to your postcode →

What the data tells us

1
81.5% of rear extension applications in Merton get approved. That means 1,041 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
2
Your ward matters more than you think. The 16.7% gap between Lower Morden (100.0%) and Raynes Park (83.3%) 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

1,041 rear extension applications in Merton 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 Merton planning data

Nearby councils rear extension data

Methodology: Based on 5,617 planning decisions classified as rear extensions in Merton, 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 Merton Council's public planning portal. Full methodology →
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