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Rear Extension Approval Rates in Spelthorne

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 296 real decisions tell us about rear extension outcomes in Spelthorne.

296 real decisions·January 2020 to present·Updated March 2026
88.2%
Approval Rate
296
Decisions
261
Approved
35
Refused
88.2% approved. But 35 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 Spelthorne: Shepperton Town approves 100.0% of rear extension applications while Ashford Common sits at 62.5%. That 37.5% gap means your postcode is one of the strongest indicators of outcome.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1Shepperton Town77
100.0%
2Sunbury Common1010
100.0%
3Staines88
100.0%
4Riverside And Laleham66
100.0%
5Halliford And Sunbury West77
100.0%
6Ashford North And Stanwell South1514
93.3%
7Ashford East1614
87.5%
8Stanwell North76
85.7%
9Ashford Town1613
81.2%
10Staines South2016
80.0%
11Sunbury East1510
66.7%
12Ashford Common1610
62.5%
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These are council averages. Your property is specific.

A rear extension has a 100.0% approval rate in Shepperton Town but just 62.5% in Ashford Common.
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 Spelthorne.

TypeDecisionsRate
Side Extension65
95.4%
Outbuilding32
93.8%
Conservatory52
90.4%
Garage / Parking88
88.6%
Rear Extension296
88.2%
Dormer79
84.8%
Loft Conversion57
84.2%
Hip-to-Gable Conversion40
82.5%
See how this applies to your postcode →

What the data tells us

1
88.2% of rear extension applications in Spelthorne get approved. That means 35 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
2
Your ward matters more than you think. The 37.5% gap between Shepperton Town (100.0%) and Ashford Common (62.5%) 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

35 rear extension applications in Spelthorne 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 Spelthorne planning data

Methodology: Based on 296 planning decisions classified as rear extensions in Spelthorne, 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 Spelthorne Council's public planning portal. Full methodology →
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