What type of planning application is most likely to be approved in Hounslow?

Conservatory at 95.0% based on 1,925 decisions.

What is hardest to get planning permission for in Hounslow?

HMO at 49.7% based on 338 decisions.

How do approval rates vary by project type in Hounslow?

From 95.0% (Conservatory) to 49.7% (HMO). What you build matters as much as where you build it.

Most Common Planning Applications in Hounslow

Not all planning applications are created equal. The gap between the highest and lowest approval project type in Hounslow is 45.3% — that's the difference between near-certainty and a coin flip. What you build matters as much as where you build it.

72,195 real decisions·17 project types·Updated March 2026

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All 17 project types ranked

#	Type	Decisions	Approved	Refused	Rate
1	Conservatory	1,925	1,828	97	95.0%
2	Extension (General)	3,033	2,817	216	92.9%
3	Dormer	1,373	1,243	130	90.5%
4	New Build	4,779	4,302	477	90.0%
5	Loft Conversion	12,007	10,774	1,233	89.7%
6	Basement	1,485	1,321	164	89.0%
7	Wraparound Extension	1,494	1,328	166	88.9%
8	Garage / Parking	8,713	7,716	997	88.6%
9	Side Extension	7,753	6,830	923	88.1%
10	Hip-to-Gable Conversion	3,244	2,770	474	85.4%
11	Rear Extension	26,504	22,511	3,993	84.9%
12	Front Extension	1,034	858	176	83.0%
13	Change of Use (Residential)	3,085	2,551	534	82.7%
14	Outbuilding	4,154	3,348	806	80.6%
15	Flat Conversion	1,402	1,022	380	72.9%
16	Annex	110	73	37	66.4%
17	HMO	338	168	170	49.7%

See how this applies to your postcode →

These are council averages. Your property is specific.

A conservatory application has a 95.0% approval rate. HMO? Just 49.7%.
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What the data tells us

The range is massive: 49.7% to 95.0%. Choosing the right project type — or framing your application correctly — can dramatically affect outcomes.

Visibility drives scrutiny. Project types that change the external appearance — dormers, loft conversions, hip-to-gable — face more resistance than those that don't. The more visible your proposal, the more carefully it needs designing.

These are council-wide averages. Your ward, your street and your immediate neighbours all shift the odds. The comparable decisions near your property are the best indicator of outcome.

Before you spend £5,000+ on architects and drawings

8,848 planning applications in Hounslow 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 Hounslow planning data

Nearby councils project type rankings

Methodology: Classifies 72,195 decisions in Hounslow into residential project types using keyword matching against proposal descriptions (matching generate_site_data.py subtype rules). A single application may appear in multiple categories. Data from Hounslow Council's public planning portal, January 2020 to present. Full methodology →