Outbuilding approval rate in Hillingdon

Hillingdon approved 80.2% of outbuilding applications, based on 2,618 decisions analysed.

Last updated: June 2026

80.2%

outbuilding approval rate

2,618

Outbuilding decisions

2,099

Approved

519

Refused

79.0%

Hillingdon overall

Outbuilding applications are approved at roughly the same rate as the Hillingdon average (79.0%).

How outbuilding compares in Hillingdon

Outbuilding (2,618 decided)

80.2%

Hillingdon all applications (30,584 decided)

79.0%

Planning a outbuilding in Hillingdon?

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Other project types in Hillingdon

Rear Extension (10,118 decided)

77.8%

Garage / Parking (7,611 decided)

81.0%

Dormer (4,882 decided)

78.5%

Side Extension (4,825 decided)

71.2%

Hip-to-Gable Conversion (2,252 decided)

83.5%

Extension (General) (1,988 decided)

83.0%

New Build (1,672 decided)

80.4%

Change of Use (Residential) (1,480 decided)

74.4%

Front Extension (1,069 decided)

65.6%

Wraparound Extension (983 decided)

76.1%

Flat Conversion (917 decided)

73.1%

Conservatory (852 decided)

81.9%

Loft Conversion (487 decided)

74.3%

Basement (482 decided)

84.2%

HMO (339 decided)

57.5%

Annex (128 decided)

41.4%

← All Hillingdon planning statistics

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