Data-backed planning intelligence · 2,500,000+ decisions analysed across England

Rear Extension Approval Rates in Hillingdon

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 9,930 real decisions tell us about rear extension outcomes in Hillingdon.

9,930 real decisions·January 2020 to present·Updated March 2026
77.6%
Approval Rate
9,930
Decisions
7,701
Approved
2,229
Refused
77.6% approved. But 2,229 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 Hillingdon: BELMORE 2022 approves 100.0% of rear extension applications while WOOD END 2022 sits at 71.4%. That 28.6% gap means your postcode is one of the strongest indicators of outcome.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1BELMORE 202277
100.0%
2PINKWELL 202255
100.0%
3RUISLIP 202255
100.0%
4HILLINGDON EAST 202255
100.0%
5ICK/HAM & S HF/D 2255
100.0%
6EASTCOTE 202287
87.5%
7WOOD END 202275
71.4%
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These are council averages. Your property is specific.

A rear extension has a 100.0% approval rate in BELMORE 2022 but just 71.4% in WOOD END 2022.
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 Hillingdon.

TypeDecisionsRate
Basement478
84.1%
Hip-to-Gable Conversion2,238
83.6%
Extension (General)1,957
83.0%
Conservatory832
81.9%
Garage / Parking7,547
80.9%
New Build1,644
80.0%
Outbuilding2,572
80.0%
Dormer4,830
78.4%
Rear Extension9,930
77.6%
Wraparound Extension947
75.8%
Change of Use (Residential)1,439
74.8%
Loft Conversion475
73.7%
Flat Conversion914
73.0%
Side Extension4,767
70.9%
Front Extension1,057
65.5%
HMO319
59.6%
Annex125
40.8%
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What the data tells us

1
77.6% of rear extension applications in Hillingdon get approved. That means 2,229 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
2
Your ward matters more than you think. The 28.6% gap between BELMORE 2022 (100.0%) and WOOD END 2022 (71.4%) 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

2,229 rear extension applications in Hillingdon 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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Free instant check · Pro Report £79 · Based on 2,500,000+ real decisions

More Hillingdon planning data

Nearby councils rear extension data

Methodology: Based on 9,930 planning decisions classified as rear extensions in Hillingdon, 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 Hillingdon Council's public planning portal. Full methodology →
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