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Rear Extension Approval Rates in Brentwood

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 3,957 real decisions tell us about rear extension outcomes in Brentwood.

3,957 real decisions·January 2020 to September 2026·Updated September 2026
83.5%
Approval Rate
3,957
Decisions
3,306
Approved
651
Refused
83.5% approved. But 651 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 Brentwood.

TypeDecisionsRate
Conservatory764
86.1%
Extension (General)449
84.0%
Rear Extension3,957
83.5%
Garage / Parking3,322
83.2%
Front Extension986
83.2%
Annex200
82.0%
Side Extension2,251
81.8%
Basement168
81.0%
Outbuilding782
79.8%
Wraparound Extension419
79.7%
New Build338
76.9%
Change of Use (Residential)406
76.8%
Hip-to-Gable Conversion278
76.3%
Dormer1,477
73.1%
Loft Conversion562
70.1%
Flat Conversion43
67.4%
See how this applies to your postcode →

What the data tells us

1
83.5% of rear extension applications in Brentwood get approved. That means 651 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

651 rear extension applications in Brentwood 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 3,840,000+ real decisions

More Brentwood planning data

Nearby councils rear extension data

Methodology: Based on 3,957 planning decisions classified as rear extensions in Brentwood, January 2020 to September 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 Brentwood Council's public planning portal. Full methodology →
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