Flat roofs on Shoreham-by-Sea extensions, garages and outbuildings require specification appropriate to local conditions. We install GRP fibreglass and EPDM rubber flat roofing to a standard that lasts 30-40 years in this climate.
Moisture retention from the Adur valley accelerates felt underlay decay — flat roofs and older pitched roofs both affected. The flat roofs on Shoreham-by-Sea's extensions, garages and outbuildings require the right material specification for local conditions. We install GRP as our first choice in exposed positions.
River Adur creates elevated ground-level humidity across the town — higher than neighbouring Hove despite similar coastal position. Flood plain properties see accelerated moss growth and increased felt underlay decay from sustained damp. South-westerly exposure from the river mouth. Correct fall and drainage specification is critical in Shoreham-by-Sea's rainfall pattern. We survey the existing structure, assess drainage routes, and specify falls that clear the roof surface within 24 hours of rainfall stopping.
We always strip to the deck before installation. Common findings on Shoreham-by-Sea properties: saturated OSB or plywood deck from years of felt failure; joist rot from sustained moisture; inadequate insulation. We document all findings before quoting for extra work — never proceed without your agreement.
A GRP flat roof in Shoreham-by-Sea requires minimal maintenance — an annual inspection and clearing of any debris from outlets. EPDM requires lap joint inspection every 2-3 years in West Sussex conditions. We carry out free annual inspections for all flat roofing customers for the first 5 years after installation.
| GRP fibreglass (per sqm installed) | £70 - £90 |
| EPDM rubber (per sqm installed) | £55 - £75 |
| Kitchen extension (20-25 sqm) | £1,400 - £2,250 |
| Garage (20-30 sqm) | £1,400 - £2,700 |
| Larger area (40-60 sqm) | £2,800 - £5,400 |
“Old felt roof on the extension had been leaking for two years. GRP installed in a day and a half. Looks completely different and I have no doubt it will outlast everything else on the property.”
“Replaced the garage felt with GRP. Quick, tidy and they found some deck rot I wasn't aware of — fixed it and showed me before proceeding. Honest job.”
“Third flat roof replacement in 30 years on the same extension. Went with GRP this time on their advice. Should be the last time I ever need to do it.”
Victorian and Edwardian terraces near the High Street, 1930s semis along Brighton Road, 1920s-30s houseboat-era bungalows on Shoreham Beach. Mixed clay tile on Victorian stock, concrete interlocking on 1930s-50s expansion, original slate on some Edwardian properties..
River Adur creates elevated ground-level humidity — higher than neighbouring Hove. Flood plain properties see accelerated moss and felt decay..
The Adur Valley humidity accelerates felt underlay decay on flat roofs and older pitched roofs. Bungalow flat sections fail faster here than equivalent inland properties..
Pricing note: Flood plain properties see higher ongoing maintenance costs than elevated equivalents — budget for more frequent guttering and valley work..
Every job follows the same clear process — no surprises, no hidden costs, full communication throughout.
We inspect the existing membrane, check drainage falls, assess the deck condition and identify any structural issues before quoting.
All existing felt or membrane stripped. Deck inspected thoroughly — any rot or saturation documented and quoted for before work proceeds.
Deck repaired or replaced where needed. Any drainage issues corrected. Falls assessed and improved where possible.
New membrane installed to manufacturer specification. GRP: full lamination across the entire deck as a single membrane. All upstands, outlets and penetrations correctly detailed.
10-year written workmanship guarantee issued. Free annual inspection for the first 5 years after installation.
GRP fibreglass is our recommendation for most Shoreham-by-Sea properties. It forms a seamless, jointless membrane with no lap joints to fail, resists UV well, and has an expected life of 30-40 years. EPDM is suitable for sheltered positions. Traditional felt is not recommended for West Sussex conditions.
GRP fibreglass is £70-90 per sqm installed. A typical kitchen extension (20-25 sqm) costs £1,400-£2,250. A double garage (40 sqm) costs £2,800-£3,600. All prices include stripping the old felt and debris disposal.
GRP fibreglass correctly installed lasts 30-40 years in West Sussex conditions. EPDM lasts 20-30 years. Traditional felt lasts 8-12 years. The significant lifespan difference justifies the higher upfront cost of GRP for most customers.
Replacing a flat roof with the same material and specification is permitted development. Changing the roof type (e.g. adding a raised parapet or changing the drainage system significantly) may require planning approval. We advise on this during the free survey.
Yes — this is the most common flat roofing job we carry out. We strip all existing felt, inspect and repair the deck if needed, and install a GRP system directly over the existing structure in most cases.
10-year written workmanship guarantee on all GRP and EPDM installations. The GRP material itself carries a manufacturer guarantee of 25 years.
We cover Shoreham-by-Sea and the surrounding area including Hove, Portslade, Lancing. Call 01273 973 996 to arrange a free survey.
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