Harrow at a glance
- Postcode districts
- HA3, HA1, HA2, HA7, HA5, HA8, HA6
- Council area
- London Borough of Harrow
- Building approval
- London Borough of Harrow building control, or a registered building control approver
- Guide price region
- London (+20% on West Midlands rates)
When should a flat roof in Harrow be replaced?
Flat roofs in Harrow get replaced for the same reasons as anywhere else: the covering has reached the end of its service life, leaks keep returning after repairs, or water ponds because the deck has sagged. Once the boards are soft or the insulation is wet, a full strip usually costs less than another round of patching.
In and around Harrow, flat roofs are typically found on mansard and dormer loft conversions, and on kitchen extensions and roof terraces behind period houses. The Thames basin is one of the drier parts of Britain at roughly 730 mm of rain a year, but summer heat is the bigger test here: dark membranes on south-facing roofs swing a long way in temperature.
How much does a flat roof replacement cost in Harrow?
At London guide rates, a 20 m² extension roof in EPDM with a new deck and insulation comes to £3,350–£5,850 including VAT. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM, new deck + insulation | £3,350–£5,850 |
| Single garage (18 m²), torch-on felt | £1,800–£3,150 |
| Extension (20 m²), GRP, new deck + insulation | £3,600–£6,450 |
| Single garage (18 m²), EPDM rubber | £1,900–£3,350 |
Which system should I replace my flat roof with?
The right system depends on the roof's size, shape, use and number of details, so no single material suits every roof. These are the usual starting points:
- EPDM rubber suits simple, rectangular roofs, where one sheet can often cover the area with few or no joins.
- GRP fibreglass suits roofs with many corners, rooflights or edges, and gives a rigid surface for occasional maintenance traffic.
- Torch-on felt is a layered, hard-wearing system that keeps the cost down on larger or plain roofs.
- Liquid-applied systems handle awkward details and can overlay a sound existing surface.
- Single-ply and mastic asphalt are more usual on commercial roofs, blocks and terraces.
We recommend a system at survey and explain why. Our EPDM vs GRP vs felt guide sets out the trade-offs if you want to compare first.
What's included?
- New membrane, upstands, edge trims and outlets
- Free survey of the deck, falls, edges and insulation
- Strip-out of the old covering, with waste and skip
- New deck, firrings and warm-roof insulation where needed
Building regulations in England
Replacing more than half of a flat roof over a heated room usually counts as renovating a thermal element, so the roof is insulated to around 0.16 W/m²K where that's technically and economically feasible, and the work is notified to building control: the council or a registered building control approver, unless a registered competent person self-certifies it. A roof on a new extension is built to 0.15 W/m²K. Patch repairs, and most unheated detached garages, don't trigger the upgrade. Structural changes, or a new covering that adds 15% or more to the roof's weight, also need approval. More on the rules.
Which nearby areas do we also cover?
Flat roof replacement in Harrow: questions
Do you cover Harrow?
Yes. Harrow is part of our London coverage, including postcode districts HA3, HA1, HA2, HA7, HA5, HA8 and 1 more. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in Harrow?
Where the work needs approval it goes to London Borough of Harrow building control, or a registered building control approver. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does a flat roof replacement cost in Harrow?
£3,350–£5,850 for a 20 m² extension roof in EPDM with a new deck and insulation, at London guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
What guarantees come with a replacement roof?
Every re-roof comes with a written workmanship guarantee, with the length set out in your quote. Manufacturer material guarantees are available on many systems and we register them for you where the system allows; ask about insurance-backed options too.
Do I need to be at home while the roof is replaced?
Not for most of the job, as long as the team can reach the roof and there is room for a skip. We ask you to be there at the start to agree the plan and at the end to look over the finished roof.