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Loft Conversion Approval Rates in Hillingdon

Loft conversions change your roofline — and that makes them one of the more closely scrutinised application types. Councils scrutinise visibility, overlooking and street character more closely than for ground-level work. Here's what the data shows in Hillingdon.

487 real decisions·January 2020 to present·Updated June 2026
74.3%
Approval Rate
487
Decisions
362
Approved
125
Refused
74.3% approved. But 125 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 loft conversion approval rates matter

Loft conversions face more scrutiny than rear or side extensions because they change the property's profile from the street. Dormers, mansards and hip-to-gable alterations are particularly sensitive.

These are council averages. Your property is specific.

Two houses on the same street can get different outcomes.
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How loft conversions compare to other project types

Not all applications are treated equally. Here's how loft conversions stack up against other common projects in Hillingdon.

TypeDecisionsRate
Basement482
84.2%
Hip-to-Gable Conversion2,252
83.5%
Extension (General)1,988
83.0%
Conservatory852
81.9%
Garage / Parking7,611
81.0%
New Build1,672
80.4%
Outbuilding2,618
80.2%
Dormer4,882
78.5%
Rear Extension10,118
77.8%
Wraparound Extension983
76.1%
Change of Use (Residential)1,480
74.4%
Loft Conversion487
74.3%
Flat Conversion917
73.1%
Side Extension4,825
71.2%
Front Extension1,069
65.6%
HMO339
57.5%
Annex128
41.4%
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What the data tells us

1
74.3% of loft conversion applications in Hillingdon get approved. That means 125 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

125 loft conversion applications in Hillingdon 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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More Hillingdon planning data

Nearby councils loft conversion data

Methodology: Based on 487 planning decisions classified as loft conversions in Hillingdon, 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 Hillingdon Council's public planning portal. Full methodology →
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