Data-backed planning intelligence · 3,780,000+ decisions analysed across England

Rear Extension Approval Rates in Horsham

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 2,214 real decisions tell us about rear extension outcomes in Horsham.

2,214 real decisions·January 2020 to August 2026·Updated August 2026
95.2%
Approval Rate
2,214
Decisions
2,107
Approved
107
Refused
95.2% approved. But 107 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 Horsham.

TypeDecisionsRate
Conservatory469
98.3%
Basement34
97.1%
Wraparound Extension333
97.0%
Side Extension1,378
96.2%
Front Extension408
96.1%
Rear Extension2,214
95.2%
Loft Conversion243
94.7%
Dormer700
91.7%
Hip-to-Gable Conversion82
91.5%
Extension (General)463
90.3%
Outbuilding627
89.6%
Garage / Parking2,251
88.5%
Annex155
83.9%
New Build817
78.9%
Flat Conversion30
76.7%
Change of Use (Residential)717
73.2%
See how this applies to your postcode →

What the data tells us

1
95.2% of rear extension applications in Horsham get approved. That means 107 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

107 rear extension applications in Horsham 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 3,780,000+ real decisions

More Horsham planning data

Nearby councils rear extension data

Methodology: Based on 2,214 planning decisions classified as rear extensions in Horsham, January 2020 to August 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 Horsham Council's public planning portal. Full methodology →
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