GRP fibreglass, EPDM rubber and built-up felt flat roofing for extensions, garages and outbuildings across Bath. Long-lasting systems with manufacturer warranties and no call-out fees for assessments.
Flat roofing in Bath costs 900 to 6,000 pounds, with GRP fibreglass the recommended choice — seamless and lasting 25 to 30 years. We install and repair flat roofs on extensions, garages and outbuildings with a 25-year manufacturer warranty. Free assessment, no call-out fee. Call 0122 528 7924.
Flat roofs fail at the surface and the details: a blistered or split membrane, standing water that never clears, or a leak at an upstand or outlet. Most Bath flat-roof problems are old felt reaching the end of its life.
Water ponding on the roof days after rain
Blisters, splits or cracks in the felt or covering
A leak into the room or extension below
Felt lifting at edges or around the outlet
A roof that's been patched repeatedly
When it is not the answer: If your flat roof is a sound GRP or EPDM system under 15 years old with one isolated fault, a targeted repair is far cheaper than a full replacement — we'll tell you honestly which you need. Read the full guide.
Warm deck versus cold deck flat roof construction compared
Flat Roofing in Bath
Long-Life Flat Roofing Solutions in Bath
Bath has a high proportion of Victorian and Georgian properties with rear additions and extensions on flat roofs. Many of these are now 20 to 40 years old on a traditional felt system that is approaching or past its useful life. Bath's above-average annual rainfall and the tendency for damp valley microclimates in the Avon basin accelerate felt degradation compared with drier inland locations.
GRP Fibreglass Flat Roofing
GRP (glass-reinforced polyester) is now the most popular flat roofing system in Bath for extensions and garages. It is laid as a seamless single-piece membrane, is chemically welded at all upstands and details, and carries a 25-year manufacturer warranty when installed by an approved applicator. Service life of 30 to 40 years is realistic with correct installation. It handles Bath's wet winters better than felt alternatives and is not affected by UV degradation.
EPDM Rubber Flat Roofing
EPDM (ethylene propylene diene monomer) is a cold-applied single-ply rubber membrane suited to larger flat roof areas and more complex geometries. It is particularly useful on rear extensions with awkward abutments to stone walls or parapet details typical of Bath's period housing stock. EPDM carries a 20-year warranty and a design life of 50 years.
Flat Roof Costs in Bath
Garage flat roof (GRP): £900–£1,800
Extension flat roof (GRP, up to 20sqm): £1,500–£3,000
Extension flat roof (EPDM, up to 40sqm): £2,500–£5,000
Prices vary with access, existing deck condition, and any drainage work required.
Flat roof leaking? Call 0122 528 7924 for a free assessment. We diagnose the problem and advise repair or replacement honestly — no upsell.
We inspect the deck, falls and current covering, and identify why it's failing rather than just patching the symptom.
2. Recommend & quote
We recommend GRP or EPDM based on the roof and setting, and quote a fixed price including any deck and insulation work.
3. Scheduling
We book the job — most flat roofs are a one to three-day project — and confirm access.
4. Strip & re-lay
We strip to the deck, re-establish proper falls, upgrade insulation to current regs, and lay the new seamless covering.
5. Finish & sign-off
We complete the trims and outlets, clear the site, and hand over your guarantee and any manufacturer warranty.
Timescales
Job Durations at a Glance
Job
Typical duration
Flat roof repair
2–4 hours
Garage flat roof (GRP/EPDM)
1 day
Extension flat roof
1–2 days
Large or multi-level flat roof
2–4 days
Deck replacement
+1 day
GRP needs dry conditions to cure, so we watch the forecast and won't lay fibreglass into rain — EPDM is more weather-tolerant.
Access
Getting Safely onto Bath Roofs
Most Bath flat roofs are reached from a tower or ladder; scaffold is added only for higher or awkward extensions and is itemised. Scaffold is specified for: first-floor and above flat roofs, or where edge protection is required - always itemised in your written quote, never a hidden extra, and we arrange it.
Bath's Georgian and Victorian terraces mean tight pavements, controlled parking, and rear-access scaffold on many streets. Pavement scaffold and skip permits go through Bath & North East Somerset Council; allow a few working days on streets like Milsom Street, Broad Street, Margaret's Buildings where space is tight.
Pricing
What Flat Roofing Costs in Bath
Job
Typical range
Notes
Flat roof repair
£150–£450
Isolated fault
Garage flat roof (EPDM)
£800–£1,800
Single-ply rubber
Garage flat roof (GRP)
£1,000–£2,200
Seamless fibreglass
Extension flat roof
£1,800–£4,000
Size dependent
Large/multi-level flat roof
£3,000–£6,000+
Incl. insulation upgrade
What moves the price
Roof area and number of outlets, upstands and details
GRP fibreglass vs EPDM rubber vs the setting
Whether the deck and insulation need replacing to meet regs
Access height on first-floor and above extensions
Worked example: A GRP fibreglass replacement on a typical rear kitchen extension in Bear Flat, including a new deck and upgraded insulation: around £2,600.
No deposit on flat-roof repairs under £500. Staged payment on full replacements, balance on completion — never anything before materials are on site. VAT included.
Covering BA1, BA2 and surrounding postcodes.
Guarantee
Your Guarantee, Explained
Our flat-roof workmanship is guaranteed for 10 years; GRP and EPDM systems carry manufacturer warranties of 20–25 years on top when installed to spec.
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 roofing is quiet, quick work with minimal mess — usually done in a day or two with the old covering taken away and the area left clean. You do not need to stay home for external work - we just need power and access agreed in advance.
GRP laying waits for a dry window; EPDM can go on in most conditions. Either way we never leave a deck exposed overnight. Bath's valley setting holds humidity, so north-facing slopes dry slowly and moss builds up through autumn.
Customer Reviews
Flat Roofing Customers in Bath
★★★★★
“Garage roof had been leaking for two winters. Bath Roofing stripped the old felt, checked the decking, replaced two rotten boards, and installed a GRP fibreglass finish. No more leaks, 25-year warranty, done in a day.”
Nick B. · Bathampton, Bath
★★★★★
“Rear extension flat roof needed replacing on our Victorian terrace in Widcombe. They matched the parapet height carefully, ensured correct drainage fall, and the GRP finish looks clean and professional.”
Helen S. · Widcombe, Bath
★★★★★
“EPDM rubber roof on our workshop at the bottom of the garden. Good price, quick installation, no mess left behind. Recommended without hesitation.”
Graham C. · Keynsham
Free assessments available across Bath and all surrounding Somerset and Wiltshire areas. We cover the full BA1, BA2, BA3, BS31, BA11, BA14, BA15, SN12, SN13 and SN14 postcodes. All assessments include a written condition report and a fixed-price quote before any work starts. No call-out fee. 10-year workmanship guarantee. NFRC registered and fully insured. Call 0122 528 7924 to arrange a survey within 2 to 5 working days, or for emergency attendance within 60 to 90 minutes. Our own team carries out all work — no subcontractors, no third-party lead generation. The roofer who surveys your property is the same team who completes the job.
FAQ
Frequently Asked Questions
A standard garage flat roof replacement in Bath costs between 900 and 1,800 pounds depending on size and system. Extension flat roofs typically cost between 1,500 and 5,000 pounds. GRP fibreglass is the most popular choice for longevity. We provide free quotes for all flat roofing work.
A correctly installed GRP fibreglass flat roof has a design life of 25 to 40 years and comes with a 25-year manufacturer warranty when installed by an approved applicator. It is seamless, resistant to UV degradation, and requires minimal maintenance.
Yes. We assess drainage as part of every flat roof survey and will recommend drainage improvements alongside any repair or replacement work. Poorly drained flat roofs on Bath properties, particularly rear extensions, are a common cause of premature membrane failure.
Flat roof replacements on existing structures are typically permitted development. New flat roofed extensions may require permission. We advise on this as part of every quote and can flag any conservation area considerations for properties in the World Heritage Site zone.
A correctly installed GRP fibreglass roof has a design life of 30 to 40 years and carries a 25-year manufacturer warranty. It handles Bath's above-average rainfall and Avon valley humidity significantly better than traditional felt alternatives.
GRP is accepted on flat roof surfaces that are not visible from the public realm on most Bath listed buildings and conservation area properties. Where the roof surface is visible, lead or traditional felt may be required. We advise on the appropriate system as part of every survey.
GRP fibreglass is a rigid seamless system suited to smaller and medium flat roofs up to around 100 square metres. EPDM rubber is a flexible membrane better suited to larger roof areas, complex geometries, and surfaces with movement or deflection. Both carry long warranties — we recommend the appropriate system for each job rather than defaulting to one material.
