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Rear Extension Approval Rates in Blackburn with Darwen

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 2,166 real decisions tell us about rear extension outcomes in Blackburn with Darwen.

2,166 real decisions·January 2020 to present·Updated March 2026
90.2%
Approval Rate
2,166
Decisions
1,953
Approved
213
Refused
90.2% approved. But 213 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
1Unknown5454
100.0%
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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 Blackburn with Darwen.

TypeDecisionsRate
Conservatory310
92.6%
Hip-to-Gable Conversion69
91.3%
Rear Extension2,166
90.2%
Annex88
89.8%
Garage / Parking1,389
88.8%
Outbuilding282
88.7%
Side Extension1,057
88.3%
Front Extension157
87.9%
Extension (General)1,911
87.8%
Basement101
87.1%
Wraparound Extension215
85.6%
New Build450
84.0%
Loft Conversion62
83.9%
Dormer559
81.9%
Change of Use (Residential)1,076
78.6%
Flat Conversion102
71.6%
HMO29
55.2%
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What the data tells us

1
90.2% of rear extension applications in Blackburn with Darwen get approved. That means 213 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

213 rear extension applications in Blackburn with Darwen 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 Blackburn with Darwen planning data

Methodology: Based on 2,166 planning decisions classified as rear extensions in Blackburn with Darwen, 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 Blackburn with Darwen Council's public planning portal. Full methodology →
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