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Rear Extension Approval Rates in Caerphilly

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 989 real decisions tell us about rear extension outcomes in Caerphilly.

989 real decisions·January 2020 to September 2026·Updated September 2026
80.8%
Approval Rate
989
Decisions
799
Approved
190
Refused
80.8% approved. But 190 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 Caerphilly.

TypeDecisionsRate
HMO40
92.5%
Conservatory143
86.0%
Rear Extension989
80.8%
Change of Use (Residential)558
79.9%
Extension (General)471
77.5%
Garage / Parking1,038
76.9%
Side Extension605
75.9%
Dormer259
75.3%
Wraparound Extension89
74.2%
New Build58
74.1%
Loft Conversion98
72.4%
Basement32
71.9%
Outbuilding209
71.3%
Annex73
71.2%
Flat Conversion28
60.7%
Front Extension83
53.0%
See how this applies to your postcode →

What the data tells us

1
80.8% of rear extension applications in Caerphilly get approved. That means 190 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

190 rear extension applications in Caerphilly 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 Caerphilly planning data

Nearby councils rear extension data

Methodology: Based on 989 planning decisions classified as rear extensions in Caerphilly, 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 Caerphilly Council's public planning portal. Full methodology →
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