By Basingstoke Roofing Experts · Call 0125 624 2410 for a free quote
If your flat roof needs replacing — and across Basingstoke's estates, thousands of original felt flat roofs are well past their expiry date — the choice comes down to two modern systems: EPDM rubber membrane or GRP fibreglass. Both are vastly superior to felt. Here is how to choose between them.
EPDM is a synthetic rubber membrane supplied in large sheets that are bonded to the roof deck. It is flexible, lightweight, and fast to install. A typical garage roof can be completed in a single day. EPDM handles thermal movement well — it stretches and contracts without cracking — and carries a typical guarantee of 20–25 years. It is the budget-friendly option for simple, rectangular flat roof areas where minimal detail work is needed.
GRP is applied as liquid resin and glass fibre matting that cures into a rigid, seamless shell. It bonds to every surface it touches — upstands, edge trims, drainage outlets, pipe penetrations — creating a single watertight membrane with no joints, laps or seams. GRP is harder, more resistant to foot traffic, and offers a 25-year guarantee as standard. It is the premium option for extensions, dormer roofs, balconies, and any area with complex details.
For a standard single garage flat roof (approx 15m²): EPDM typically costs £800–£1,200, GRP costs £1,200–£1,800. For a rear extension flat roof (approx 25m²): EPDM costs £1,500–£2,500, GRP costs £2,500–£3,500. The price difference narrows on complex roofs where GRP's seamless application saves labour on detail work that EPDM requires more time to seal.
For a simple garage roof or shed: EPDM is the sensible choice. It does the job, costs less, and installs faster. For a rear extension, dormer, or any roof you might walk on: GRP is the better investment. Its rigidity, seamless finish, and resistance to foot traffic justify the premium. For system-built properties in South Ham and Popley where flat roof sections are integral to the building: GRP is our standard recommendation because the stakes are higher — failure means water directly into the living space.
Local coverage: Flat roofing in Kingsclere · Flat roofing in Whitchurch
Roofing is one of the few trades where the customer usually cannot see the work being discussed. That asymmetry is why getting a second opinion on any significant quote is sensible — not because most roofers are dishonest, but because specifications genuinely vary and comparing them is the only way to know what you are buying.
When comparing quotes, look past the headline figure. Does each quote include scaffold? Are materials named by manufacturer or described vaguely as "quality tiles"? Is waste disposal included? Is there a written guarantee, and what does it actually cover? A quote that is £500 cheaper but omits scaffold and dry ridge is not cheaper at all.
Ask what happens if additional problems are found once work starts. A good answer describes a process: stop, photograph, discuss, agree cost, then continue. A vague answer suggests you may face unexpected charges. Ask what guarantee is provided and request it in writing. Ask whether the guarantee transfers if you sell — a transferable guarantee is a genuine selling point.
Finally, ask for references from recent local work. Any roofer confident in their standards will provide them readily, and following up two or three takes ten minutes that could save you thousands.
The National Federation of Roofing Contractors publishes technical guidance for homeowners covering material selection, standards compliance and choosing a contractor. Your local authority building control department can advise on when notification or approval is required. For conservation area and listed building work, the Basingstoke and Deane conservation officer is the definitive source on what materials will be acceptable.
For anything specific to your own roof, a professional inspection is worth more than any amount of general reading. Call 0125 624 2410 — advice costs nothing and there is no obligation to book work.
Call 0125 624 2410 for a free, no-obligation quote from a local Basingstoke roofer.
EPDM is better for simple, rectangular areas like garages — it is cheaper and faster to install. GRP is better for complex shapes, walkable surfaces, and areas where failure would cause serious damage — like extensions and system-built property sections.
20–25 years with proper installation and minimal maintenance. High-quality EPDM products like Firestone carry manufacturer warranties of 20 years.
25–30+ years. GRP cures into a rigid, seamless shell with no joints to fail. It is the most durable flat roofing system available for domestic properties.
GRP resin cures chemically and requires a minimum temperature of around 5°C to set properly. In Basingstoke's winters, this limits installation to milder days between October and March. EPDM is less temperature-sensitive and can be installed in colder conditions.
Felt flat roofing has a 10–15 year lifespan. EPDM lasts 20–25 years, GRP lasts 25–30+. Over 30 years, felt would need replacing twice while GRP or EPDM would still be performing. The long-term cost of felt is higher than either modern alternative.
Depends on its condition. If the existing timber decking is dry, level, and structurally sound, it can be retained. If it is rotten, uneven, or sagging, replacement with new marine-grade plywood is essential for a proper installation. We assess every job individually.
Modified bitumen torch-on felt is a step up from traditional felt but still relies on lapped joints that can fail over time. It typically lasts 15–20 years — better than basic felt but shorter than EPDM or GRP. For the modest price difference, we recommend EPDM or GRP for a longer-lasting solution.
No call-out fees. No obligation. Just an honest quote from a local Basingstoke roofer who'll turn up when they say they will.
0125 624 2410