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Most Common Planning Applications in Hertsmere

Not all planning applications are created equal. The gap between the highest and lowest approval project type in Hertsmere is 17.5% — that's the difference between near-certainty and a coin flip. What you build matters as much as where you build it.

1,943 real decisions·16 project types·Updated September 2026
100.0%
Safest: HMO
82.5%
Lowest: New Build
17.5%
Spread
16
Types ranked

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All 16 project types ranked

#TypeDecisionsApprovedRefusedRate
1HMO27270
100.0%
2Flat Conversion28280
100.0%
3Front Extension1621548
95.1%
4Wraparound Extension1211156
95.0%
5Basement32302
93.8%
6Hip-to-Gable Conversion14513510
93.1%
7Garage / Parking54950346
91.6%
8Dormer51447044
91.4%
9Change of Use (Residential)74677
90.5%
10Extension (General)77698
89.6%
11Outbuilding16815018
89.3%
12Conservatory16914920
88.2%
13Side Extension37132546
87.6%
14Rear Extension1,3061,131175
86.6%
15Loft Conversion957916
83.2%
16New Build978017
82.5%
See how this applies to your postcode →

These are council averages. Your property is specific.

A hmo application has a 100.0% approval rate. New Build? Just 82.5%.
Check your postcode to see what actually happens near your address.

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What the data tells us

1
The range is massive: 82.5% to 100.0%. Choosing the right project type — or framing your application correctly — can dramatically affect outcomes.
2
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.
3
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

242 planning applications in Hertsmere 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 Hertsmere planning data

Methodology: Classifies 1,943 decisions in Hertsmere 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 Hertsmere Council's public planning portal, January 2020 to September 2026. Full methodology →
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