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Rear Extension Approval Rates in Portsmouth

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 2,254 real decisions tell us about rear extension outcomes in Portsmouth.

2,254 real decisions·January 2020 to present·Updated March 2026
89.2%
Approval Rate
2,254
Decisions
2,010
Approved
244
Refused
89.2% approved. But 244 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.

Ward gap in Portsmouth: Copnor approves 100.0% of rear extension applications while Milton sits at 60.0%. That 40.0% gap means your postcode is one of the strongest indicators of outcome.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1Copnor55
100.0%
2Baffins55
100.0%
3Drayton & Farlington1211
91.7%
4Cosham98
88.9%
5Hilsea65
83.3%
6Milton53
60.0%
See how this applies to your postcode →

These are council averages. Your property is specific.

A rear extension has a 100.0% approval rate in Copnor but just 60.0% in Milton.
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 Portsmouth.

TypeDecisionsRate
Conservatory219
93.2%
Outbuilding230
92.2%
Wraparound Extension46
91.3%
Rear Extension2,254
89.2%
Basement87
87.4%
Side Extension571
87.0%
Extension (General)313
85.9%
HMO1,003
85.5%
Front Extension109
85.3%
Change of Use (Residential)1,336
84.7%
Garage / Parking657
84.6%
Hip-to-Gable Conversion101
79.2%
Dormer756
78.7%
Annex36
75.0%
Loft Conversion200
75.0%
New Build27
70.4%
Flat Conversion147
68.7%
See how this applies to your postcode →

What the data tells us

1
89.2% of rear extension applications in Portsmouth get approved. That means 244 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
2
Your ward matters more than you think. The 40.0% gap between Copnor (100.0%) and Milton (60.0%) means your postcode is one of the strongest indicators of outcome.
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

244 rear extension applications in Portsmouth 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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Free instant check · Pro Report £79 · Based on 2,500,000+ real decisions

More Portsmouth planning data

Nearby councils rear extension data

Methodology: Based on 2,254 planning decisions classified as rear extensions in Portsmouth, 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 Portsmouth Council's public planning portal. Full methodology →
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