Do I need planning permission for a porch in Harrow?

Usually not, as long as it's under 3m², under 3m high, and at least 2m from the highway. Listed buildings are the exception — they always need consent.

How much does a porch cost?

A porch in London typically costs between £5,000 and £15,000 depending on materials. A simple UPVC porch is at the low end, a brick-built porch with a tiled roof at the higher end.

What is the maximum size for a porch under permitted development?

The maximum ground floor area is 3 square metres, with a maximum height of 3 metres.

Do I need Building Regulations approval for a porch?

In most cases, no. Porches are usually exempt from Building Regulations provided they are at ground level, under 30m², and have glazed walls.

Porch in Harrow: Planning Permission Guide

Everything you need to know about building a porch in Harrow — PD rules, costs, and when you need planning permission.

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Porchs in Harrow at a glance

93%

approved

£258

application fee

weeks typical

Based on 28 decided applications in Harrow over 12 months (26 granted, 2 refused).

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.

Council planning portal Pre-application advice

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Recent porch decisions in Harrow

The 5 most recent decided applications. Addresses redacted to postcode area.

Granted

Details pursuant to Condition 4 (Surface Water Attenuation and As-Built Foul Drainage) attached to planning permission PL/1745/25 dated 7…

HA22026-03-29

Granted

Details pursuant to Conditions 5 (Disposal of Sewage) and 6 (Disposal of Surface Water) attached to planning permission PL/2924/25 …

HA52026-03-29

Refused

Conversion Of Dwellinghouse into Two Flats (2 x2 Bed); Front Porch; refuse and cycle storage with dedicated amenity space

HA22026-03-29

Granted

Details pursuant to Condition 5 (Flood Mitigation Measures) attached to planning permission PL/1915/25 dated 12/09/2025 for Single st…

HA72026-03-16

Granted

Certificate of Lawful Development (Proposed): Front porch

HA52026-03-09

These are borough-wide. See the 5 nearest to your address.

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Permitted Development Rules

Class DPart 1

Porches

GPDO 2015, Schedule 2, Part 1, Class D

Porches are covered by Part 1, Class D of the GPDO. They have simple, clear rules: stay under 3 square metres, under 3 metres high, and at least 2 metres from the highway.

Key dimension limits

Max 3m² footprintMax 3m heightMin 2m from highway

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.

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Typical Costs in London

Porches are one of the more affordable home improvements, with costs depending mainly on materials and design.

PorchLondon

Cost per m²

£1,800–£3,000

construction rate

Typical total

£5,000–£15,000

Based on 2–4 m²

Typically includes

FoundationsStructureRoofDoorBasic finishes

Typically excludes

Planning application feeBuilding regs fee

Costs depend heavily on materials and finish — a simple UPVC porch is at the low end, brick-built with tiled roof at the high end.

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Which Professionals Do You Need?

Porches are relatively simple structures. In most cases, a builder can handle the project without needing an architect.

A draughtsperson or architectural technician can prepare any drawings needed. A full architect may not be necessary.

Architect / designerOptional

Porches are simple structures. A builder or draughtsperson can usually prepare any drawings needed.

Typical fee: £500–£1,500 (Basic drawings)

Structural engineerNot needed

Party wall surveyorOptional

May apply if the work is within 3 metres of a shared boundary. Check with your builder.

Typical fee: £700–£1,500 (per neighbour (if applicable))

Planning consultantNot needed

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.

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Conservation Areas & Listed Buildings

In conservation areas, the same PD rules apply to porches, but you should use materials sympathetic to the area character.

Conservation areas

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

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.

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Frequently Asked Questions

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Fence, wall or gate

GPDO Class A (Part 2)

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