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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 3,847 real decisions tell us about rear extension outcomes in Brentwood.

3,847 real decisions·January 2020 to present·Updated June 2026
84.1%
Approval Rate
3,847
Decisions
3,236
Approved
611
Refused
84.1% approved. But 611 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 Brentwood: Blackmore And Doddinghurst approves 100.0% of rear extension applications while Hutton South sits at 66.7%. That 33.3% gap means your postcode is one of the strongest indicators of outcome.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1Blackmore And Doddinghurst55
100.0%
2Shenfield88
100.0%
3Ingatestone, Fryerning And Mountnessing55
100.0%
4Herongate, Ingrave And West Horndon1010
100.0%
5Pilgrims Hatch66
100.0%
6Brentwood West54
80.0%
7Hutton North54
80.0%
8Hutton South64
66.7%
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These are council averages. Your property is specific.

A rear extension has a 100.0% approval rate in Blackmore And Doddinghurst but just 66.7% in Hutton South.
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
Conservatory750
86.4%
Extension (General)438
84.2%
Rear Extension3,847
84.1%
Garage / Parking3,235
83.5%
Front Extension963
83.3%
Side Extension2,205
82.4%
Annex196
81.6%
Outbuilding744
80.9%
Basement167
80.8%
Wraparound Extension403
79.9%
Hip-to-Gable Conversion266
78.9%
Change of Use (Residential)391
77.5%
New Build331
77.0%
Dormer1,425
73.9%
Loft Conversion545
71.6%
Flat Conversion43
67.4%
See how this applies to your postcode →

What the data tells us

1
84.1% of rear extension applications in Brentwood get approved. That means 611 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
2
Your ward matters more than you think. The 33.3% gap between Blackmore And Doddinghurst (100.0%) and Hutton South (66.7%) 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

611 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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More Brentwood planning data

Nearby councils rear extension data

Methodology: Based on 3,847 planning decisions classified as rear extensions in Brentwood, 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 Brentwood Council's public planning portal. Full methodology →
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