The Selsey peninsula is one of the most demanding environments for flat roofing in the South. We install GRP fibreglass and EPDM rubber exclusively here — coastal UV and salt air make felt a false economy.
Flat roofing on the Selsey peninsula presents challenges that simply don't exist 10 miles inland. The combination of extreme UV exposure from the southern coastal position, salt-laden air arriving from three compass points, and the near-constant wind movement across the flat peninsula creates a working environment that is genuinely hostile to traditional felt flat roofing systems.
The bungalow stock that dominates Selsey's housing is extensively extended — rear additions, garage conversions, glazed link extensions and annexes are very common across the peninsula, and the vast majority of these additions have flat roofs. Most were originally laid in mineral felt, and the majority of those are now past end of design life. We replace Selsey flat roofs exclusively with GRP fibreglass or EPDM rubber — felt replacement is not something we recommend in this location as the lifespan differential makes it poor long-term value.
GRP fibreglass (extension): £1,500–£3,500 · EPDM rubber (garage): £1,200–£3,000 · Felt replacement (not recommended, available on request): £800–£2,000 · Free quotes on all jobs.
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01243 278085"GRP flat roof on our bungalow rear extension in East Beach — replacing 1970s felt that had failed in three places. The GRP is perfect, completely seamless, no issues in two full winter seasons."
"EPDM on our double garage roof — they explained the coastal specification clearly and why felt wasn't the right choice here. The system they installed looks and performs exactly as they described."
"Full flat roof inspection followed by GRP replacement on our link extension. Very thorough survey, clear quote, no surprises on the day. Best roofing experience we've had."
Selsey bill is the most southerly point of west sussex and the most exposed location in our entire coverage area — three sides of the peninsula face open sea and the wind loading here is exceptional. For flat roofing in Selsey this means we carry out more post-storm emergency call-outs per property in Selsey than anywhere else we cover — the combination of low pitch, aging fixings and severe wind exposure creates a consistently high-risk profile. The town is predominantly bungalow and low-pitch residential from the 1950s onwards, with a significant number of properties that have had repeated storm damage from south-westerly gales. Full mechanical fixing throughout — tiles, ridge and hip — is our standard recommendation for any selsey re-roof, not just the exposed elevations.
On Selsey's exposed coastal position, the UV intensity and salt aerosol make the choice of flat roof system more consequential than on sheltered inland sites. GRP fibreglass performs well but requires careful installation — the gelcoat must be mixed and applied within the correct temperature range, which is not always achievable on exposed coastal sites in cooler weather. EPDM rubber has no temperature-sensitivity constraints during installation and its single-ply membrane has excellent resistance to UV and ozone degradation. For Selsey flat roofs, EPDM is our preferred specification where the installation conditions are uncertain.
A standard bungalow extension flat roof replacement in Selsey costs £1,000–£2,500 for EPDM rubber and £1,500–£3,500 for GRP fibreglass depending on size. We recommend GRP or EPDM over felt for all Selsey properties given the coastal exposure — felt lifespans are significantly reduced in this environment.
GRP fibreglass is our primary recommendation for the Selsey peninsula. Its seamless surface, UV resistance, and long design life (25+ years) makes it the most appropriate system for the extreme coastal exposure here. EPDM rubber is a close second for larger garage roofs. We do not recommend felt replacement as a long-term solution for Selsey — coastal UV and salt air reduce felt lifespan to 8–12 years at best.
Both. We patch and seal damaged GRP and EPDM sections, and repair felt blistering where the underlying structure is still sound. If more than 30% of the flat roof is affected, replacement is usually more cost-effective — we advise honestly after survey.
A standard bungalow extension flat roof replacement typically takes 1–2 days. Larger garage or multi-section roofs may take 2–3 days. We carry all materials to site and rarely need to source anything once work starts.
Blistering, cracking, pooling water after rain, or felt that has become soft and spongy to walk on are all signs a replacement is needed rather than a patch repair. If a felt flat roof is over 12 years old in Selsey's coastal climate and showing any of these signs, replacement with GRP or EPDM is almost always the more cost-effective long-term decision.
Replacing a flat roof like-for-like on a house extension or outbuilding is generally permitted development in Selsey. Changing the height or footprint, or work on a listed building or in a conservation area, may require consent. We advise at the survey stage.
Correct drainage is the single most important factor in flat roof longevity. All our flat roof installations include assessment of falls, outlet positioning and gutter connections before work starts. We correct any drainage deficiencies as part of the installation — a new flat roof laid to inadequate falls will fail early regardless of the material quality.
Every flat roof survey covers: the existing deck condition (whether the existing decking boards are sound or require replacement), the current falls (whether adequate drainage exists or whether tapered insulation is needed to correct the falls), the upstand heights (whether the covering can be taken up to the required minimum height at edges and abutments), and the outlet position and sizing. In Selsey, where the most exposed coastal location with three-sided sea exposure, we also assess whether coastal UV intensity or harbour moisture exposure affects the system recommendation. A flat roof that drains correctly and has proper upstand details lasts decades longer than one where these fundamentals were not addressed at installation.
GRP fibreglass is applied as a liquid laminate that cures to a rigid seamless surface. We apply two layers of chopped strand mat saturated with resin, followed by the coloured gelcoat finish. The entire surface is seamless — no joints to open, no laps to fail. Upstands are formed to the correct height and radius at all edges. Outlets are GRP-lined. The gelcoat provides UV protection that significantly outlasts felt surface treatment in Chichester's coastal UV environment. Installation requires temperatures above 5°C — we plan flat roof work around weather forecasts to ensure the correct curing conditions.
A standard single-car garage flat roof in GRP typically costs £900 to £1,800 in Selsey. Rear extension flat roofs up to 25m² cost £1,800 to £4,000. Larger areas of 25 to 60m² run £3,500 to £7,500. These prices include deck inspection, any necessary deck replacement, falls correction where needed, full GRP lamination and gelcoat finish. EPDM rubber costs approximately 10 to 15 per cent less than GRP on the same area with comparable performance over the long term.
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