Wraparound extension in Harrow: Planning Permission Guide
Your guide to wraparound extensions in Harrow — combining rear and side extensions under one project.
Check if your wraparound extension qualifiesWraparound extensions in Harrow at a glance
approved *
application fee
weeks typical
Based on 15 decided applications in Harrow over 12 months (14 granted, 1 refused). * Limited data — treat as indicative.
Harrow has conservation areas around Harrow-on-the-Hill (a distinctive hilltop village with very strict design controls), Pinner, and Stanmore. Listed buildings are concentrated in Harrow-on-the-Hill and around Harrow School. Green Belt borders the north and west of the borough around Stanmore Common and Harrow Weald. Article 4 Directions cover parts of Harrow-on-the-Hill. The borough has a mix of inter-war semis, garden suburb character, and older village cores.
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Approval probability, 5 nearest comparables, refusal reasons — for your specific address.
Recent wraparound extension decisions in Harrow
The 5 most recent decided applications. Addresses redacted to postcode area.
Certificate of Lawful Development (Existing): Alterations and extension to roof; side and rear dormers
Certificate of lawful development (proposed): Alterations to roof to form wrap around rear dormer with two rooflights; installation of th…
Certificate of Lawful Proposed Development: Alterations to roof to form end gable and rear dormer Three roof lights in front roof slo…
Certificate of Lawful Development (Proposed): Wrap around rear dormer; two rooflights in both side roof slopes
Certificate of Lawful Proposed Development: Alterations to roof to form end gable and side and rear dormers; External alterations (De…
These are borough-wide. See the 5 nearest to your address.
Get my report — £9Permitted Development Rules
Enlargement, improvement or other alteration of a dwellinghouse
GPDO 2015, Schedule 2, Part 1, Class A
A wraparound extension combines a rear and side extension. It's assessed under Part 1, Class A of the GPDO and must comply with the limits for both rear depth and side width.
Key dimension limits
These are the maximum GPDO limits for a detached house with no constraints. Your actual limits depend on your property type, location, and any planning restrictions.
Enter your postcode to see the personalised limits for your wraparound extension.
Check my limitsTypical Costs in London
Wraparound extensions cost more than a simple rear or side extension due to the larger footprint and more complex structural requirements.
Cost per m²
construction rate
Typical total
Based on 20–30 m²
Typically includes
Typically excludes
Combines rear and side extension. Costs at the higher end due to larger footprint and structural complexity.
Get a personalised cost estimate based on your actual wraparound extension dimensions.
Get my estimateWhich Professionals Do You Need?
Wraparound extensions have complex geometry with multiple roof junctions and typically benefit from professional design input.
You'll need a party wall surveyor for this project.
Wraparound extensions have complex geometry with multiple roof junctions that benefit from professional design.
Typical fee: £2,000–£5,000 (Plans + Building Regs)
Single storey extensions typically need structural calculations for any openings in existing walls and for foundations.
Typical fee: £500–£1,500
Your semi-detached house shares a boundary with neighbours. Extensions and loft work within 3 metres of a shared wall trigger the Party Wall Act.
Typical fee: £700–£1,500 (per neighbour)
This guidance is based on a typical semi-detached house with no special constraints. Listed buildings, conservation areas, and attached properties may require additional professional input.
Find out exactly which professionals you need for your wraparound extension.
Get personalised guidanceConservation Areas & Listed Buildings
In conservation areas, the side element of a wraparound extension is not permitted development. The rear element is limited to 3 metres depth.
Properties in conservation areas often have reduced permitted development rights. Some project types (like side extensions) lose PD rights entirely. An Article 4 Direction can remove additional PD rights.
Listed buildings (Grade I, II*, or II) have no permitted development rights at all. Any external alteration requires Listed Building Consent in addition to any planning permission. An architect experienced in heritage work is essential.
Check if your property is in a conservation area or has other planning constraints.
Check my propertyFrequently Asked Questions
Just want a quick yes/no for your wraparound extension?
Run our free 2-minute check to see whether your project likely qualifies as permitted development in Harrow. For personalised approval odds and nearby comparables, get the full report above.
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