Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 364 real decisions tell us about rear extension outcomes in Cardiff.
See your ward's approval rate and nearby planning decisions — free and instant.
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 | Decisions | Approved | Rate |
|---|---|---|---|---|
| 1 | WHITCHURCH AND TONGWYNLAIS | 5 | 5 | 100.0% |
| 2 | CYNCOED | 6 | 6 | 100.0% |
| 3 | HEATH | 7 | 6 | 85.7% |
A rear extension has a 100.0% approval rate in WHITCHURCH AND TONGWYNLAIS but just 85.7% in HEATH.
Check your postcode to see what actually happens near your address.
Not all applications are treated equally. Here's how rear extensions stack up against other common projects in Cardiff.
| Type | Decisions | Rate |
|---|---|---|
| Flat Conversion | 26 | 88.5% |
| Dormer | 216 | 85.6% |
| Hip-to-Gable Conversion | 63 | 84.1% |
| Front Extension | 24 | 83.3% |
| HMO | 29 | 82.8% |
| Annex | 28 | 78.6% |
| Outbuilding | 81 | 77.8% |
| New Build | 21 | 71.4% |
| Loft Conversion | 205 | 70.2% |
| Rear Extension | 364 | 67.9% |
| Garage / Parking | 293 | 66.9% |
| Extension (General) | 293 | 66.6% |
| Side Extension | 154 | 65.6% |
| Change of Use (Residential) | 89 | 59.6% |
| Conservatory | 176 | 49.4% |
117 rear extension applications in Cardiff 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.
Check my postcode