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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 1,350 real decisions tell us about rear extension outcomes in Mid Sussex.

1,350 real decisions·January 2020 to October 2026·Updated October 2026
95.4%
Approval Rate
1,350
Decisions
1,288
Approved
62
Refused
95.4% approved. But 62 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 Mid Sussex.

TypeDecisionsRate
Conservatory370
97.3%
Front Extension247
95.5%
Rear Extension1,350
95.4%
Side Extension776
95.1%
Wraparound Extension103
93.2%
Basement29
93.1%
Outbuilding472
92.8%
Loft Conversion382
92.7%
Hip-to-Gable Conversion80
92.5%
Extension (General)564
92.2%
Garage / Parking1,500
92.0%
Dormer521
91.6%
Change of Use (Residential)262
88.9%
Annex76
86.8%
New Build174
76.4%
See how this applies to your postcode →

What the data tells us

1
95.4% of rear extension applications in Mid Sussex get approved. That means 62 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

62 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 3,850,000+ real decisions

More Mid Sussex planning data

Nearby councils rear extension data

Methodology: Based on 1,350 planning decisions classified as rear extensions in Mid Sussex, January 2020 to October 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 Mid Sussex Council's public planning portal. Full methodology →
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