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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 439 real decisions tell us about rear extension outcomes in Caerphilly.

439 real decisions·January 2020 to present·Updated March 2026
85.6%
Approval Rate
439
Decisions
376
Approved
63
Refused
85.6% approved. But 63 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.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1Machen And Rudry54
80.0%
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These are council averages. Your property is specific.

Two houses on the same street can get different outcomes.
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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
Conservatory62
90.3%
New Build23
87.0%
Rear Extension439
85.6%
Outbuilding67
85.1%
Loft Conversion49
83.7%
Garage / Parking403
82.9%
Change of Use (Residential)111
81.1%
Extension (General)225
80.9%
Dormer103
78.6%
Side Extension257
77.8%
Annex26
76.9%
Wraparound Extension38
73.7%
Front Extension33
57.6%
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What the data tells us

1
85.6% of rear extension applications in Caerphilly get approved. That means 63 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

63 rear extension applications in Caerphilly have been refused since 2020. Many of those homeowners had already paid for drawings and application fees. A £79 report shows you what gets approved — and what gets refused — near your property.

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More Caerphilly planning data

Nearby councils rear extension data

Methodology: Based on 439 planning decisions classified as rear extensions in Caerphilly, 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 Caerphilly Council's public planning portal. Full methodology →
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