Do I need planning permission to change my roof tiles?

Not usually, as long as the new materials don't project beyond the existing roof plane. In conservation areas, you should match the existing materials.

Can I add rooflights without planning permission?

Generally yes, under Class C, as long as they don't project more than 150mm beyond the roof plane.

How much does a roof alteration cost?

Roof alteration costs in London typically range between £5,000 and £15,000, with rooflights at the cheaper end and a full re-roof with new materials at the higher end.

Do I need Building Regulations for a roof alteration?

Depending on the work, you may need Building Regulations approval for structural changes, insulation, or fire safety requirements.

Project guideGPDO Class C

Roof alteration in Harrow: Planning Permission Guide

What you need to know about roof alterations in Harrow — re-roofing, rooflights, and changing materials.

81%

approved in Harrow

£548

application fee

8 wks

typical decision

≤0.15m

rooflight proud

Based on 21 decided applications in Harrow over 24 months (17 granted, 4 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

Local data PD rules Costs Professionals Constraints FAQs

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5 nearest comparables & refusal reasons for your address.

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Recent roof alteration decisions in Harrow

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

Granted

Variation of condition 2 (Approved Plans) attached to planning permission PL/0682/25 dated 15/08/2025 to allow installation of two roof l…

HA12026-06-14

Refused

Certificate of Lawful Proposed Development: Installation of solar panels to garage roof

HA52026-06-07

Refused

replacement of roof tiles and side timber framed window

HA52026-05-31

Granted

Replacement roof tiles; Roof light in rear roof slope

HA12026-05-17

Adjoining Borough Consultations No Objection

Consultation from Neighbouring Authority: London Borough of Hertsmere: Reference 26/0353/HSE; Single storey and first floor side infill …

WD232026-05-10

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

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Permitted Development Rules

Class CPart 1

Any other alteration to the roof of a dwellinghouse

GPDO 2015, Schedule 2, Part 1, Class C

Roof alterations (other than dormers and loft conversions) are covered by Part 1, Class C of the GPDO. The key rule is that the alteration must not project beyond the existing roof plane.

Key dimension limits

Must not project beyond existing roof planeMaterials must match existing

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

Roof alteration costs vary depending on the scope — adding rooflights is much cheaper than a full roof replacement.

Roof alterationLondon

Cost per m²

£800–£2,000

construction rate

Typical total

£5,000–£15,000

Typically includes

MaterialsLabourScaffolding

Typically excludes

Planning application feeBuilding regs fee

Covers re-roofing, changing roof materials, adding rooflights. Full roof replacement is at the higher end.

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Which Professionals Do You Need?

Most roof alterations don't need an architect, but a roofing contractor or draughtsperson can prepare any required drawings.

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

Architect / designerOptional

Roof alterations may need drawings for Building Regulations, but a draughtsperson or roofing contractor can often provide these.

Typical fee: £500–£2,000 (Basic drawings if needed)

Structural engineerNot needed

Party wall surveyorNot needed

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, roof alterations that change the appearance of the roof may be more tightly controlled. Materials should match the existing roof.

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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Related guides

Loft conversion

GPDO Class B

Dormer

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