Clear flat roofing prices for Chichester — GRP fibreglass and EPDM rubber for extensions, garages and outbuildings. Long-life seamless systems with 20-year warranties, not short-lived felt. Free survey.
A flat roof in Chichester costs £900–£1,800 for a garage, £1,800–£4,000 for an extension, and up to £5,500 for larger EPDM areas. GRP and EPDM both far outlast felt in the coastal climate, with 20-year warranties. Free survey, no call-out fee. Call 01243 278085.
Flat roofing cost in Chichester depends on the system, the area, and the deck condition beneath. GRP fibreglass and EPDM rubber are the two systems we install — both dramatically outlast the traditional felt they replace, which is a false economy in Chichester's coastal UV environment.
GRP cures to a seamless rigid surface with no joints to open. A single garage roof costs £900–£1,800; an extension flat roof up to 25m² runs £1,800–£4,000. The UV-stable gelcoat gives a design life of 25–40 years, three to four times that of felt. We back GRP with a 20-year manufacturer guarantee.
EPDM single-ply membrane is installed in large sheets — often one sheet for a whole garage — with no seams to fail. Larger areas of 25–60m² cost £3,500–£5,500. Its flexibility handles building movement without cracking, and its design life of 30–50 years suits larger and more exposed flat roofs across the Chichester coastal area.
Chichester's flat roofing demand comes largely from the rear extensions and garages that were added to the city's post-war and interwar housing stock. The 1930s semis of Summersdale and the post-war estates of Portfield and Donnington almost all have a flat-roofed rear addition or detached garage, and the original felt on these — long past its 8–12 year life — is the most common flat roof we're called to replace.
The coastal position matters more for flat roofs than most homeowners realise. The intense UV exposure on the Chichester coastal plain degrades felt surface treatment faster than inland, and the salt-laden air adds to the load. This is precisely why we don't install felt on any new flat roof here — the upfront saving is recovered in the first replacement cycle and lost several times over across 30 years.
On the most exposed coastal locations — Selsey, East Wittering, the harbour-edge properties in Bosham and Pagham — we favour EPDM over GRP. GRP installation requires temperatures above 5°C for correct curing, which isn't always achievable on exposed coastal sites in cooler weather, whereas EPDM has no such constraint and its single-ply membrane handles the wind and UV loading of these positions exceptionally well.
Prices include deck inspection, any necessary deck replacement, falls correction where needed, and the full system installation with warranty. Chichester sits at the southern England baseline for labour. Felt is not offered for any new installation.
GRP and EPDM single-ply systems carry manufacturer design lives of 25 to 50 years, compared with 8 to 12 years for traditional built-up felt.
— GRP and EPDM manufacturer technical specifications
Failed felt flat roof? Get a free GRP or EPDM quote — no call-out fee
📞 01243 278085A flat roof installation is a controlled process, and the quality of the result depends as much on preparation and detailing as on the membrane itself. Here is how ours works.
We start by assessing the existing deck. Old felt flat roofs frequently hide soft or rotten decking beneath, and laying a new system over a failing deck guarantees early failure. Where the deck is sound we lay straight onto it; where it is not, we replace it at £25–£45/m². We also check the falls — a flat roof is never truly flat, and correct falls to the outlet are what stop ponding. All of this is assessed and priced at survey.
We match the system to the roof. GRP fibreglass gives a hard, seamless, walk-on surface ideal for smaller areas and where appearance matters. EPDM rubber, installed in large single sheets, suits larger areas and the most exposed coastal positions where its flexibility and lack of installation-temperature constraint are decisive. We explain the choice at survey rather than defaulting to whichever we prefer to fit.
Most flat roof failures happen at the edges and junctions, not in the field of the roof. Correct upstands against adjoining walls, proper trims at the eaves, and well-formed outlets are what make the difference between a 25-year roof and a five-year one. Our installations detail these correctly, which is why they carry a 20-year warranty.
The intense UV and salt exposure of the Chichester coastal plain is exactly the environment that punishes cheap flat roofing. Felt degrades fastest here, which is why we do not fit it new. GRP and EPDM are specified precisely because they hold up to the coastal loading for decades. On the most exposed sites — Selsey, East Wittering, the harbour edges — EPDM is our default for its resilience. The right system chosen once, correctly installed, is the cheapest flat roof over any realistic timescale.
Every flat roof carries a 20-year manufacturer guarantee on the membrane plus our own 10-year workmanship guarantee. GRP and EPDM both need minimal maintenance — an occasional clear of debris from outlets — and we are on hand if anything ever needs attention.
The two systems we install — GRP fibreglass and EPDM rubber — are both excellent, and the right choice depends on the specific roof. Here is how they compare for Chichester conditions.
GRP cures to a hard, seamless, walk-on surface with a high-quality finish, making it ideal for smaller roofs, balconies and anywhere appearance matters or foot traffic is expected. Its design life is 25–40 years. The one constraint is installation: GRP needs dry conditions above 5°C to cure correctly, so on exposed coastal sites in cooler weather the working window can be limited.
EPDM is a flexible single-ply membrane installed in large sheets — often a single sheet covers an entire garage with no seams to fail. Its design life is 30–50 years, and it handles building movement and thermal cycling without cracking. It has no installation-temperature constraint, which makes it the reliable choice on the exposed coastal and peninsula sites — Selsey, East Wittering, the harbour edges — where GRP's curing window is harder to hit.
We match the system to the roof rather than defaulting to one. Smaller, visible or trafficked roofs often favour GRP; larger, exposed or movement-prone roofs favour EPDM. On the most weather-exposed Chichester positions EPDM is our default for its resilience and installation reliability. We explain the choice at survey with the reasoning, so you understand why we are recommending what we are recommending — and both carry the same 20-year warranty.
"Replaced the failed felt on our Summersdale extension with GRP. Seamless finish, no more leaks, and a proper 20-year guarantee."
"EPDM on our Selsey garage — they recommended it over fibreglass for the exposed position and explained exactly why. Spot on."
"Our Portfield garage roof was a felt disaster. They stripped it, replaced the decking and fitted GRP. Excellent job, fair price."
A garage flat roof in Chichester costs £900–£1,800 in GRP, an extension flat roof £1,800–£4,000, and larger EPDM areas £3,500–£5,500. Prices include deck inspection, any deck replacement, and the full system with a 20-year warranty.
Both are excellent. GRP suits smaller areas and gives a hard, seamless finish. EPDM suits larger areas and the most exposed coastal sites — Selsey, East Wittering, the harbour villages — because it has no installation temperature constraint and handles movement well. We advise on the right choice at survey.
Traditional felt lasts only 8–12 years in Chichester's coastal UV environment, versus 25–50 years for GRP and EPDM. The upfront saving on felt is recovered in the first replacement cycle and lost several times over across 30 years, so we don't fit it on new work.
If the existing deck is sound we lay the new system straight onto it. If it is soft or rotten — common under old felt — we replace it at £25–£45/m². We assess the deck at survey and include any replacement in the written quote.
A garage flat roof is usually a one-day job. An extension flat roof takes one to two days. GRP needs dry conditions above 5°C for correct curing, so we plan the work around the forecast.
Yes. We back every GRP and EPDM installation with a 20-year manufacturer guarantee plus our own 10-year workmanship guarantee. Full credentials are available on request.
Sometimes, if the failure is localised and the rest of the system is sound. More often, a failed felt roof is at the end of its life and replacement in GRP or EPDM is the better value. We give you the honest assessment at survey.
GRP and EPDM systems built to last, from a local Chichester roofer. Free survey, no call-out fee.
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