Outbuilding approval rate in Hillingdon

Hillingdon approved 80.0% of outbuilding applications, based on 2,572 decisions analysed.

Last updated: March 2026

80.0%

outbuilding approval rate

2,572

Outbuilding decisions

2,058

Approved

514

Refused

78.9%

Hillingdon overall

Outbuilding applications are approved at roughly the same rate as the Hillingdon average (78.9%).

How outbuilding compares in Hillingdon

Outbuilding (2,572 decided)

80.0%

Hillingdon all applications (30,009 decided)

78.9%

Planning a outbuilding in Hillingdon?

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Other project types in Hillingdon

Rear Extension (9,930 decided)

77.6%

Garage / Parking (7,547 decided)

80.9%

Dormer (4,830 decided)

78.4%

Side Extension (4,767 decided)

70.9%

Hip-to-Gable Conversion (2,238 decided)

83.6%

Extension (General) (1,957 decided)

83.0%

New Build (1,644 decided)

80.0%

Change of Use (Residential) (1,439 decided)

74.8%

Front Extension (1,057 decided)

65.5%

Wraparound Extension (947 decided)

75.8%

Flat Conversion (914 decided)

73.0%

Conservatory (832 decided)

81.9%

Basement (478 decided)

84.1%

Loft Conversion (475 decided)

73.7%

HMO (319 decided)

59.6%

Annex (125 decided)

40.8%

← All Hillingdon planning statistics

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