Data-backed planning intelligence · 3,290,000+ decisions analysed across England

Rear Extension Approval Rates in Mid Sussex

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 1,282 real decisions tell us about rear extension outcomes in Mid Sussex.

1,282 real decisions·January 2020 to present·Updated June 2026
95.5%
Approval Rate
1,282
Decisions
1,224
Approved
58
Refused
95.5% approved. But 58 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 Mid Sussex: Hassocks approves 100.0% of rear extension applications while Lindfield sits at 50.0%. That 50.0% gap means your postcode is one of the strongest indicators of outcome.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1Hassocks55
100.0%
2Cuckfield, Bolney And Ansty53
60.0%
3Lindfield63
50.0%
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These are council averages. Your property is specific.

A rear extension has a 100.0% approval rate in Hassocks but just 50.0% in Lindfield.
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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 Mid Sussex.

TypeDecisionsRate
Conservatory344
97.1%
Front Extension234
96.2%
Rear Extension1,282
95.5%
Side Extension734
95.1%
Wraparound Extension96
93.8%
Outbuilding442
93.4%
Loft Conversion357
93.3%
Basement29
93.1%
Extension (General)536
92.2%
Garage / Parking1,425
92.0%
Hip-to-Gable Conversion72
91.7%
Dormer494
91.5%
Change of Use (Residential)245
89.0%
Annex70
87.1%
New Build169
76.3%
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What the data tells us

1
95.5% of rear extension applications in Mid Sussex get approved. That means 58 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
2
Your ward matters more than you think. The 50.0% gap between Hassocks (100.0%) and Lindfield (50.0%) 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

58 rear extension applications in Mid Sussex 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 3,290,000+ real decisions

More Mid Sussex planning data

Nearby councils rear extension data

Methodology: Based on 1,282 planning decisions classified as rear extensions in Mid Sussex, 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 Mid Sussex Council's public planning portal. Full methodology →
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