Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 10,671 real decisions tell us about rear extension outcomes in Harrow.
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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.
Two houses on the same street can get different outcomes.
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 Harrow.
| Type | Decisions | Rate |
|---|---|---|
| Hip-to-Gable Conversion | 66 | 86.4% |
| Conservatory | 588 | 80.8% |
| Outbuilding | 1,794 | 78.8% |
| New Build | 63 | 77.8% |
| Front Extension | 1,922 | 77.3% |
| Extension (General) | 923 | 76.7% |
| Garage / Parking | 3,725 | 76.4% |
| Wraparound Extension | 290 | 75.9% |
| Rear Extension | 10,671 | 75.4% |
| Dormer | 4,314 | 74.6% |
| Side Extension | 4,286 | 73.7% |
| Loft Conversion | 119 | 70.6% |
| Basement | 268 | 69.8% |
| Flat Conversion | 278 | 63.3% |
| Change of Use (Residential) | 761 | 62.5% |
| HMO | 304 | 55.6% |
| Annex | 78 | 43.6% |
2,628 rear extension applications in Harrow 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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