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Rear Extension Approval Rates in Buckinghamshire

Rear extensions are the bread and butter of UK planning — and one of the most common reasons homeowners face a refusal. Here's what 8,150 real decisions tell us about rear extension outcomes in Buckinghamshire.

8,150 real decisions·January 2020 to present·Updated June 2026
87.7%
Approval Rate
8,150
Decisions
7,146
Approved
1,004
Refused
87.7% approved. But 1,004 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 Buckinghamshire: Chalfont St Giles and Little Chalfont approves 100.0% of rear extension applications while Marlow sits at 80.0%. That 20.0% gap means your postcode is one of the strongest indicators of outcome.

Rear Extension approval rate by ward

#WardDecisionsApprovedRate
1Chalfont St Giles and Little Chalfont66
100.0%
2Iver55
100.0%
3Marlow54
80.0%
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These are council averages. Your property is specific.

A rear extension has a 100.0% approval rate in Chalfont St Giles and Little Chalfont but just 80.0% in Marlow.
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 Buckinghamshire.

TypeDecisionsRate
Conservatory997
90.1%
Wraparound Extension788
89.2%
Front Extension2,362
89.1%
Side Extension4,582
88.3%
Basement264
88.3%
Rear Extension8,150
87.7%
Hip-to-Gable Conversion460
84.8%
Dormer2,775
84.5%
Loft Conversion1,742
84.2%
Garage / Parking6,040
83.8%
Extension (General)959
83.2%
Annex255
82.7%
Outbuilding1,932
82.0%
Flat Conversion146
79.5%
New Build1,361
76.9%
Change of Use (Residential)1,097
76.1%
HMO89
69.7%
See how this applies to your postcode →

What the data tells us

1
87.7% of rear extension applications in Buckinghamshire get approved. That means 1,004 homeowners since 2020 have been refused. Not terrible odds, but not a foregone conclusion.
2
Your ward matters more than you think. The 20.0% gap between Chalfont St Giles and Little Chalfont (100.0%) and Marlow (80.0%) 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

1,004 rear extension applications in Buckinghamshire 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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Free · Property report emailed in minutes · Based on 3,290,000+ real decisions

More Buckinghamshire planning data

Nearby councils rear extension data

Methodology: Based on 8,150 planning decisions classified as rear extensions in Buckinghamshire, 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 Buckinghamshire Council's public planning portal. Full methodology →
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