Specialist flat roofing for extensions, garages, outbuildings and commercial properties across Farnham and Surrey. GRP fibreglass, EPDM rubber and felt systems — all installed to manufacturer specification with long-term guarantees.
Flat roofing in Farnham costs £800–£6,000 depending on material and area. GRP fibreglass is our standard recommendation — seamless, 25-year lifespan, maintenance-free. We specify correct drainage falls on every job, as ponding is the main cause of flat roof failure. Free written quotes.
Flat Roof Systems
Which Flat Roof System Is Right for You?
We install three main flat roofing systems. Each has different performance, cost and longevity characteristics. We'll recommend the right one for your project.
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Lifespan: 25–40 years
GRP Fibreglass
The premium flat roofing solution. GRP (glass reinforced plastic) creates a seamless, fully waterproof surface with no joins or seams — so no weak points. Extremely durable and virtually maintenance-free.
Seamless — no joins or seams to fail
Extremely durable and impact resistant
Low maintenance — just a periodic inspection
Can be walked on safely
Available in any colour
20-year manufacturer guarantee available
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Lifespan: 25–35 years
EPDM Rubber
Single-ply EPDM (ethylene propylene diene monomer) rubber roofing. Flexible, highly weather-resistant and cost-effective. An excellent long-term solution for most residential flat roof applications.
Excellent value for money
Highly flexible — handles movement well
Good UV and weather resistance
Lightweight system
Environmentally friendly material
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Lifespan: 10–20 years
Felt (Torch-on)
Modern torch-on felt systems use high-performance polymer-modified bitumen sheets. A proven, cost-effective solution for garages and outbuildings where budget is the primary consideration.
Most cost-effective option
Proven and widely understood
Quick installation
Good for garage and shed roofs
Where We Install Flat Roofs
Flat Roofing Applications in Farnham
We install flat roofing systems across all types of residential and light commercial properties in Farnham and the surrounding area.
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House Extensions
GRP fibreglass is ideal for single-storey rear and side extensions. Seamless finish, excellent drainage and decades of trouble-free performance.
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Garages
The most common flat roof call we receive. We replace aged felt garage roofs with modern GRP or EPDM systems that will outlast the building.
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Outbuildings
Garden rooms, home offices, studios and sheds. We specify the right system based on size, use and budget.
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Commercial Roofs
Small commercial properties and retail units across Farnham and the surrounding Surrey area. We work out of hours where required.
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Dormer Cheeks
Flat-roofed dormers on loft conversions are a common leak source. We replace and waterproof dormer roofs to stop persistent ingress.
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Roof Terraces
GRP fibreglass is the preferred system for walkable flat roofs and roof terraces — safe underfoot, slip resistant and fully waterproof.
Pricing Guide
Flat Roof Costs in Farnham
Costs depend on roof size, system chosen and access requirements. These are typical ranges for common flat roof projects in the Farnham area.
Job Type
System
Typical Cost
Single garage flat roof
GRP Fibreglass
£900 – £1,800
Single garage flat roof
EPDM Rubber
£700 – £1,400
Double garage flat roof
GRP Fibreglass
£1,500 – £3,000
Extension flat roof (up to 20m²)
GRP Fibreglass
£1,800 – £3,500
Extension flat roof (20–40m²)
GRP Fibreglass
£3,000 – £5,500
Felt garage roof replacement
Torch-on Felt
£600 – £1,200
* All prices include stripping existing surface, new decking if required, system installation and all edging details. Call for a free site visit and exact quote.
Flat roofs fail in recognisable ways. Here’s when your Farnham flat roof needs attention.
Standing water (ponding) that doesn’t drain after rain
Blistering, cracking or splitting in the felt or membrane
A leak into the room or garage below the flat roof
The felt is decades old and reaching the end of its life
Seams lifting or the surface going soft underfoot
When it is not the answer: If your flat roof is sound and just needs a small localised patch, that’s a repair, not a replacement — we’ll tell you honestly which yours needs rather than pushing a full re-cover. Read the full guide.
Warm deck versus cold deck flat roof constructionThe process
What to Expect: Flat Roofing in Farnham
1. Survey and material advice
We check the deck and falls, and advise honestly whether felt, EPDM or GRP suits your roof and budget.
2. Itemised quote
You get a clear quote including strip-off, deck repair, membrane, correct falls and any insulation upgrade.
3. Schedule around weather
We schedule the work, factoring in curing conditions for GRP, and confirm the timeline.
4. Laid and guaranteed
We lay the new roof with correct falls, clear up, and guarantee it — up to 20 years on GRP.
Timescales
How Long Does It Take?
Job
Typical duration
Flat roof repair
1 day
Garage / small extension
1–2 days
Larger flat roof
2–4 days
GRP curing
Needs dry, mild weather
GRP fibreglass needs warm, dry conditions to cure, so winter installs may wait for a suitable window; EPDM and felt are less weather-critical.
Flat roof work is often at low level, worked from ladders or a tower. Scaffold is specified for: only where the flat roof is high or access is awkward - always itemised in your written quote, never a hidden extra, and we arrange it.
Farnham’s Georgian and Victorian streets around the town centre have limited frontage and controlled pavement space, so scaffold on the conservation streets needs planning and a permit. Pavement scaffold and skip permits go through Waverley Borough Council; allow a few working days on streets like Castle Street, The Borough, Downing Street where space is tight.
Guarantee
Your Guarantee, Explained
Flat roofs carry a 10-year workmanship guarantee, with GRP and EPDM systems warrantied up to 20–25 years by the manufacturer.
Covered: workmanship for 10 years, in writing, transferable if you sell.
On top: manufacturer warranties on materials (terms vary by product).
Not covered: storm or impact damage - that is an insurance matter, and we will document it for your claim.
If a fault appears in covered work, we come back and put it right. No quibbling, no re-charge.
Good to know
What It Is Like While We Work
Flat roof work is external and contained; the room below stays usable throughout in most cases. You do not need to stay home for external work - we just need power and access agreed in advance.
GRP needs dry, mild conditions to cure; we time installs accordingly. The Wey valley holds autumn moisture, and Farnham’s heavy tree cover slows drying and blocks gutters through the leaf-fall months.
Customer Reviews
Flat Roofing Reviews
★★★★★
"Had our garage roof done in GRP fibreglass after years of patching a leaking felt roof. The difference is night and day. Professional installation and absolutely no issues since."
Simon H. · Farnham, Surrey
★★★★★
"They replaced the flat roof on our rear extension with fibreglass. Absolutely no disruption, the finish is immaculate and it looks far better than the old felt. Highly recommend."
Clare M. · Fleet, Hampshire
★★★★★
"Used them to replace an EPDM roof on our garden room. They explained all the options clearly, the price was fair, and the job was done in a day. Five stars."
Tom F. · Aldershot
FAQ
Flat Roofing Questions
A properly installed GRP fibreglass roof has a lifespan of 25–40 years. It comes with a 20-year manufacturer-backed guarantee when installed by a certified installer. It is widely considered the most durable flat roofing system available for residential properties.
A single garage flat roof in GRP fibreglass typically costs £900–£1,800. Extension flat roofs range from £1,800–£5,500 depending on size and system. We provide free, itemised no-obligation quotes for all flat roofing work.
GRP fibreglass is our recommendation for most residential extensions. It's seamless so there are no joins to fail, extremely durable, and virtually maintenance-free. EPDM rubber is an excellent and slightly more cost-effective alternative with similar longevity.
Yes — if the existing roof structure is sound and damage is isolated, repair can be very cost-effective. We'll inspect the roof honestly and tell you whether repair or replacement is the better long-term investment. We won't recommend replacement if a repair will solve the problem.
