Horsham at a glance
- Postcode districts
- RH12
- Population
- about 51,472 (GeoNames)
- Council area
- Horsham District Council
- Building approval
- Horsham District Council building control, or a registered building control approver
- Nearest main town
- Crawley, about 7 miles
- Guide price region
- South East (+10% on West Midlands rates)
When should a flat roof in Horsham be replaced?
Exposure matters too. Wind lifts tired edges, and repeated wetting and drying works at old joints, so roofs in exposed spots can wear faster than the same roof somewhere sheltered. Wherever your property is in Horsham, a survey tells you whether the roof has years left or needs replacing now.
Around Horsham, flat roofs are common on lock-up garage blocks on estates and on bungalows with flat-roofed side extensions and dormers. Much of the South East sits in the drier Thames catchment at roughly 730 mm of rain a year, so the usual failures are at joints, upstands and outlets rather than from sheer volume of rain.
How much does a flat roof replacement cost in Horsham?
Guide price in Horsham: £3,100–£5,350 for a 20 m² extension roof in EPDM with a new deck and insulation, including VAT at South East rates. 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 | £3,100–£5,350 |
| Single garage (18 m²), torch-on felt | £1,650–£2,900 |
| Extension (20 m²), GRP, new deck + insulation | £3,300–£5,900 |
| Single garage (18 m²), EPDM rubber | £1,750–£3,100 |
Should I overlay my old flat roof or strip it fully?
Strip it fully if the deck is soft, the insulation is wet or the falls are wrong; an overlay only suits a dry, sound roof that already drains well. Covering a wet roof traps the moisture, and rot carries on out of sight.
An overlay also raises the roof level, eating into upstand height at walls and door thresholds, and every layer adds weight. In England, a covering that adds 15% or more to the roof's weight needs building control approval. Signs it is time to replace rather than repair:
- ponding that lingers long after rain
- blisters, cracking or crazing across wide areas
- bare bitumen where the mineral chippings have gone
- split laps and lifted upstands or flashings
- damp ceilings, or a deck that has gone soft
- leaks that return after each repair
A single defect on an otherwise dry roof can usually be put right with a repair. If you're unsure, a survey settles it, and our guides to overlay or strip and repair or replace go further.
What's included?
- Free survey of the deck, falls, edges and insulation
- Building control handled where needed, plus a written workmanship guarantee
- 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?
- Crawley · 7 mi
- Horley · 11 mi
- Haywards Heath · 11 mi
- Burgess Hill · 11 mi
- Dorking · 12 mi
- Reigate · 13 mi
Flat roof replacement in Horsham: questions
Do you cover Horsham?
Yes. Horsham is part of our West Sussex coverage, including postcode districts RH12. 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 Horsham?
Where the work needs approval it goes to Horsham District Council 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 Horsham?
£3,100–£5,350 for a 20 m² extension roof in EPDM with a new deck and insulation, at South East guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
What time of year is best for a flat roof replacement?
Late spring to early autumn gives the most reliable dry spells, but a roof can be replaced in any season when the forecast allows. Adhesives and resins have minimum application temperatures, so winter work is planned around mild, dry days.
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.