⭐ 4.9/5 · 164 Google Reviews · NFRC Registered · Last updated: August 2026
Flat Roofing in West London
Flat roofs on extensions, garages, dormers and outbuildings need specialist attention. We install GRP fibreglass, EPDM rubber membrane and high-performance built-up felt systems — each specified to suit the size, use and exposure of your flat roof. Every installation includes proper falls, drainage and upstand detailing.
Flat roofing in West London costs £800–£6,000. We install GRP fibreglass and EPDM rubber membrane systems on extensions, garages and outbuildings. Minimum 1:40 falls, proper upstand detailing, and 25–40 year expected lifespan. Call 0203 302 2547 for a free quote.
✓ NFRC Registered · Last updated: August 2026
✓ Fully Insured
✓ 10 Year Guarantee
✓ Free Quotes
✓ No Hidden Costs
✓ Serving West London Since 2004
Flat Roofing
Flat Roofing Across West London
Flat roofs on extensions, garages, dormers and outbuildings need specialist attention. We install GRP fibreglass, EPDM rubber membrane and high-performance built-up felt systems — each specified to suit the size, use and exposure of your flat roof. Every installation includes proper falls, drainage and upstand detailing.
Flat Roof Drainage in West London — Getting It Right
The most common flat roof failure in West London is inadequate drainage. Original felt roofs from the 1960s-80s were often laid with insufficient fall — water pools, UV breaks down the membrane, and leaks follow. We install minimum 1:40 falls on every job using tapered insulation boards.
Deck Inspection — What We Find Under the Old Roof
Before any new flat roof goes on in West London, we strip back to the deck and inspect the timber. In West London properties, we commonly find rotten timber decking from years of water ingress. Catching this before the new membrane goes down saves a callback later.
GRP vs EPDM — Which Is Right for Your West London Property
GRP fibreglass gives a seamless, rigid surface that handles foot traffic — ideal for balconies and walkable roofs. EPDM rubber is flexible, handles movement well, and comes in single sheets that eliminate seam failures. For most West London extensions under 20m², GRP is our recommendation.
Typical Flat Roofing Prices
Flat Roofing across West London: £800–£6,000 depending on scope, access and materials. We provide free, written, no-obligation quotes for all work. Call 0203 302 2547 for a quote.
"Chimney stack partial rebuild and re-render — called on a weekday and they were out within days. Professional, tidy, and the price was exactly as quoted. Highly recommend."
Nicky T. · West London, London
★★★★★
"Emergency roof repair after a branch came through the tiles — called on a weekday and they were out within days. Professional, tidy, and the price was exactly as quoted. Highly recommend."
Owen W. · Ealing, London
★★★★★
"Moss removal and full roof clean — called on a weekday and they were out within days. Professional, tidy, and the price was exactly as quoted. Highly recommend."
Penelope G. · Fulham, London
FAQ
Frequently Asked Questions
A typical single-storey rear extension flat roof in West London costs £1,200–£3,000 depending on size and system. Garage roofs run £800–£2,000. Larger commercial or multi-section flat roofs can be £4,000–£6,000+.
GRP fibreglass lasts 30-40 years with minimal maintenance. EPDM rubber membrane lasts 25-30 years. Traditional felt typically lasts 10-15 years. We recommend GRP or EPDM for any flat roof in West London — the upfront cost is recovered many times over in lifespan.
Yes — GRP fibreglass is seamless, UV-stable, impact-resistant and lasts 2-3 times longer than felt. The only advantage felt has is lower upfront cost, which is a false economy over 20+ years.
If the membrane is sound but a localised area has failed, we can patch repair. If the membrane is blistered, cracked or ponding across more than 20% of its area, full replacement is more cost-effective.
Under current Building Regulations, any flat roof replacement must include insulation to meet thermal performance standards. We install rigid insulation boards above the deck, which also creates the correct drainage falls.
The three most common causes in West London are: ponding water from inadequate falls, membrane failure at upstands and abutments, and blocked outlets. All three are preventable with correct specification and installation.
A typical extension flat roof takes 1-2 days. Larger projects or those requiring significant deck repairs take 2-4 days. Weather-dependent — GRP cannot be laid in rain.
Our Process — What to Expect
Flat roof installation follows a strict sequence that cannot be shortcut. Stage one: strip the existing covering and inspect the deck. Stage two: repair or replace any damaged deck timbers — rotten OSB or plywood is the most common finding on existing flat roofs. Stage three: install tapered insulation boards to create the correct drainage falls (minimum 1:40 gradient). Stage four: apply the chosen membrane system — GRP fibreglass with resin lamination, or EPDM rubber with bonded seams. Stage five: detail all upstands, drip edges and abutments. Stage six: inspect, photograph and hand over.
Materials and Specification
GRP fibreglass creates a seamless, rigid surface that handles foot traffic and resists impact — ideal for balconies, walkable roofs and areas where you need to access equipment. EPDM rubber is flexible, accommodates structural movement, and comes in single sheets up to 15m wide that eliminate seam failures. Both systems carry 25-40 year lifespans when correctly installed. We do not install traditional felt systems for new work — the lifespan is too short to justify the labour cost of installation.
Our Guarantee
All flat roof installations carry our 10-year workmanship guarantee. GRP systems additionally carry a 25-year manufacturer guarantee on the membrane when installed by an approved contractor — which we are. EPDM carries a 20-year manufacturer guarantee on the membrane. These guarantees are meaningful because both products have track records exceeding their guarantee periods.
Flat roof problems often show up as damp patches on ceilings below. Here is how to tell whether yours needs attention.
Damp patch on the ceiling below a flat roof extension
Visible ponding or standing water after rain
Blistering, cracking or splits in the membrane surface
Moss or plant growth on the flat roof surface
Upstand seals pulling away from walls
Blocked or slow-draining outlets
When it is not the answer: If a single split or puncture is the only defect and the rest of the membrane is supple and well-adhered, a patch repair is effective and much cheaper than replacement. Read the full guide.
Warm deck vs cold deck — Building Regulations push new flat roofs to warm-deck construction.The process
From First Call to Sign-Off
1. Inspection and test strip
We inspect the membrane and strip a small test area to check the deck timber underneath.
2. Quote with system choice
GRP or EPDM recommended based on your roof size, traffic needs and budget. Full breakdown provided.
3. Strip and deck prep
Old membrane stripped. Deck inspected, repaired or replaced. Tapered insulation boards laid for correct falls.
4. Membrane installation
GRP laminated in resin or EPDM bonded in single sheet. Upstands, drip edges and outlets detailed.
5. Sign-off
Falls tested with water, photographs taken, guarantee documentation provided.
Timescales
How Long Does It Take?
Job
Typical duration
Extension flat roof (GRP)
1-2 days
Garage roof
1 day
Large dormer / balcony
2-3 days
Multi-section flat roof
3-5 days
GRP cannot be laid in rain or below 5°C. EPDM is less weather-sensitive. We schedule around forecast windows.
Access
Getting Safely onto West London Roofs
Most flat roof work is accessed from ladders or the building interior. Scaffold is only needed where the flat roof is above first-floor level. Scaffold is specified for: second-floor flat roofs, dormer roofs, and any flat roof where edge protection is required for safe working - always itemised in your written quote, never a hidden extra, and we arrange it.
Victorian terraces across Fulham, Kilburn and Willesden mean rear-access scaffold and pavement permits on busy residential streets. Pavement scaffold and skip permits go through the relevant borough council (Ealing, Hounslow, Hillingdon, Harrow, Brent, Richmond or Hammersmith & Fulham); allow a few working days on streets like Fulham Palace Road, Kilburn High Road, King Street Hammersmith, Askew Road where space is tight.
Pricing
West London Flat Roofing: Cost Guide
Job
Typical range
Notes
Extension flat roof — GRP
£1,400-£3,200
Most common residential job
Extension flat roof — EPDM
£1,200-£2,800
Single-sheet, flexible
Garage flat roof
£900-£2,200
Depends on size and access
Dormer / balcony
£1,800-£4,000
Includes edge and upstand detailing
Deck repair / replacement
£400-£1,200
Add to membrane cost if needed
What moves the price
Roof area (measured in m², not guessed)
Deck condition — rotten plywood adds £400-1,200
Insulation requirement (mandatory under Building Regs on replacement)
Upstand and abutment complexity
Access — second-floor flat roofs need scaffold
Worked example: A 14m² rear extension GRP in Acton: strip felt, replace 3 OSB boards (£180), tapered insulation (£320), GRP membrane + trim (£680), labour (£540) — total £1,720.
No deposit on jobs under £2,000. Larger projects: 30% with order (materials), balance on completion. VAT included.
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
Disruption, Mess & Weather
Minimal internal disruption. Some noise during strip. Chemical smell from GRP resin curing (ventilate well for 24 hours). You do not need to stay home for external work - we just need power and access agreed in advance.
GRP needs dry, above-5°C conditions for curing. EPDM is more forgiving. We check the forecast before scheduling. Thames corridor humidity slows drying times on riverside properties in Barnes, Chiswick and Hammersmith; elevated Harrow Hill sites face 15-20% higher wind loading.
Get In Touch
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No call-out fees. No obligation. Just an honest quote from a local West London roofer who turns up when they say they will.
