⭐ 4.9/5 · 127 Google Reviews · GRP & EPDM Specialists

Flat Roofing Cambridge

GRP fibreglass, EPDM rubber and felt flat roofing for extensions, garages and outbuildings across Cambridge. Long-lasting solutions with proper drainage and a 10-year guarantee.

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20+

Years Local

127

5★ Reviews

24/7

Emergency

10yr

Guarantee

Cambridge flat roofing in EPDM rubber and GRP fibreglass suits garages, extensions and outbuildings, costing £800–£6,000 depending on size and system. Both carry 20–25 year material warranties plus our 10-year workmanship guarantee. We inspect the deck before every quote. Call 0122 366 6465 for a free survey.

Flat Roofing

What Flat Roofing Options Do We Offer in Cambridge?

Flat roofs are everywhere in Cambridge — on rear extensions, garage blocks and outbuildings. We install and repair all types.

Flat Roofs Across Cambridge

Cambridge has thousands of flat roofs — from 1960s garage blocks across the Arbury and King's Hedges estates to rear kitchen extensions on Victorian terraces in Romsey Town and Petersfield. Many of these were originally covered in mineral felt which has a 10–15 year lifespan. If your flat roof is bubbling, cracking or holding standing water, it's time for a modern replacement that will last 25+ years.

GRP vs EPDM — Which Is Right?

GRP fibreglass gives a rigid, seamless finish that's ideal for walkable areas and balconies — popular on Cambridge's newer extensions. EPDM rubber membrane is lighter and more flexible, making it the better choice for larger roof areas and garage blocks. Both carry a 25-year life expectancy. We'll recommend the right system for your property during the survey.

Our Process

How We Install Flat Roofs

Deck Inspection

We strip the old membrane and inspect every inch of the timber deck. Soft boards, delaminated plywood and rotten joists are replaced before any new membrane goes on. Skipping this step is the number one cause of premature flat roof failure.

Fall Correction

A flat roof needs a minimum fall of 1:40 to drain water properly. If the existing deck doesn't have adequate fall, we install tapered insulation boards to create the correct drainage angle. Standing water kills flat roofs — proper falls prevent it.

Membrane Installation

For GRP: we apply a resin basecoat, embed the chopped strand mat, apply the laminating resin and finish with a UV-resistant topcoat. For EPDM: we lay the single rubber sheet, bond it to the deck with contact adhesive and seal all edges and penetrations.

Detailing and Handover

Edge trims, drip details, upstand flashings and drainage outlets are all carefully finished. These details are where flat roofs fail — we take particular care at every junction. You receive your 10-year guarantee and maintenance guidance.

Customer Reviews

What Our Customers Say

★★★★★

"New GRP flat roof on our kitchen extension. The old felt roof had been leaking for months. No more buckets — and it looks great too. Really neat, professional job."

Sarah K. · Cherry Hinton, Cambridge

★★★★★

"EPDM rubber roof on our garage. They stripped the old felt, repaired the decking underneath and fitted the new membrane in a day. Very impressed with the finish."

James C. · Arbury, Cambridge

★★★★★

"Had a flat roof on a rear extension that was holding water every time it rained. They re-laid it with a proper fall and GRP finish. Problem completely solved."

Louise T. · Queen Edith's, Cambridge

How much does a flat roof cost in Cambridge? A flat roof in Cambridge costs £800–£6,000 depending on size, system and deck condition. See the full flat roof cost guide →

Honest advice

How to Tell You Need Flat Roofing

Flat roofs fail in predictable ways. If your garage, extension or dormer roof shows any of these, it is time to look at repair or replacement.

Ponding water that sits for more than a day or two after rain
Blistering, splitting or cracking of the covering
A damp patch on the ceiling directly below the flat roof
A felt roof that is more than 15–20 years old

When it is not the answer: If the deck is sound and the covering is only locally split, a repair or overlay is cheaper than a full replacement — we will tell you honestly which yours needs. Read the full guide.

Warm deck versus cold deck flat-roof build-ups compared layer by layer; current Building Regulations favour warm-deck construction.

The process

How a Cambridge Flat Roofing Job Runs

1. Survey

We assess the covering, the falls and — as far as visible — the deck beneath, and recommend EPDM, GRP or felt.

2. Written quote

You get a fitted price with any deck-repair risk clearly flagged before we start.

3. Scheduling

We book a run of dry days for GRP; EPDM is more weather-tolerant.

4. The work

We strip the old covering, repair or replace the deck as needed, correct the falls, and lay the new membrane.

5. Cleanup & sign-off

We clear waste and hand over the guarantee and manufacturer warranty.

Timescales

Job Durations at a Glance

Job	Typical duration
Single garage roof	1 day
Extension flat roof	2–3 days
Dormer flat roof	1–2 days
Deck replacement (if needed)	Add 1 day

GRP will not cure in the wet or below 5°C, so we schedule fibreglass work around dry conditions; EPDM tolerates more.

Access

Access, Scaffolding & Permits in Cambridge

Most flat roofs are low and reached from towers; scaffold is added only for extension roofs at height or with parapets. Scaffold is specified for: first-floor extension roofs, parapet detailing, and any flat roof over a storey up - always itemised in your written quote, never a hidden extra, and we arrange it.

Victorian terraces around Romsey Town and Petersfield mean rear access is tight and pavement scaffold often needs permit-controlled space. Pavement scaffold and skip permits go through Cambridge City Council; allow a few working days on streets like Mill Road, Gwydir Street, the terraces off Petersfield where space is tight.

Pricing

What Flat Roofing Costs in Cambridge

Job	Typical range	Notes
Single garage roof (EPDM)	£800 – £1,500	Best value for garages
Single garage roof (GRP)	£1,000 – £1,800	Harder wearing
Large garage / outbuilding	£1,500 – £2,500	Per size & deck
Extension flat roof (EPDM)	£2,000 – £4,500	Damp-area choice
Extension flat roof (GRP, walkable)	£2,500 – £6,000	Walkable surface
New timber deck (per m², if needed)	£40 – £70	Only if deck has failed

What moves the price

Roof area and the number of upstands, parapets and penetrations
System choice — EPDM, GRP or felt
Deck condition beneath the old covering, only fully visible once stripped
Correcting inadequate falls to stop ponding

Worked example: Replacing a single-garage felt roof on the Arbury estate, ~18m², with new EPDM, trims and a new deck where needed, typically runs £1,100–£1,600. A 35m² walkable GRP roof over a Romsey Town kitchen extension with a rooflight kerb is nearer £3,500–£4,500.

No deposit on garage roofs under £1,500; you pay on completion. Larger roofs are staged after materials are on site. VAT included.

Guarantee

The Guarantee in Plain Terms

Our flat-roof workmanship is guaranteed for 10 years, on top of the 20–25 year manufacturer material warranties on EPDM and GRP.

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

Living Around the Work

Flat-roof work is quiet and largely out of your way; a garage or extension roof is usually done and cleared within a day or two. You do not need to stay home for external work - we just need power and access agreed in advance.

EPDM installs in most weather; GRP needs a dry window. Cambridge's damper riverside areas favour EPDM for its moisture tolerance. Cambridge's low, exposed Fen-edge position drives wind hard against gable ends, and riverside humidity near the Cam slows autumn drying.

FAQ

Frequently Asked Questions

A typical garage-sized flat roof in Cambridge costs £800–£2,500 depending on the system used. Larger extension roofs range from £2,500–£6,000. GRP is slightly more expensive than EPDM but offers a harder-wearing finish.

Modern GRP and EPDM flat roofs have a life expectancy of 25–30 years with minimal maintenance. Old felt roofs typically last 10–15 years. We always recommend upgrading to a modern system when replacing.

Yes, provided the underlying structure is sound. We can patch small areas of damage on GRP, EPDM and felt roofs. If the damage is widespread or the roof is past its design life, replacement is usually more cost-effective.

Replacing a flat roof like-for-like doesn't usually require planning permission. If you're raising the height or changing the use of the space above, you may need approval. We can advise during your free survey.

Signs include: standing water that doesn't drain within 48 hours, bubbling or cracked membrane, soft or spongy areas when walked on, and visible splits at joints or edges. If your felt roof is over 15 years old, it's likely past its useful life.

Yes. All flat roof installations carry our 10-year workmanship guarantee. GRP and EPDM systems also have manufacturer warranties of 20–25 years.

Yes. Tapered insulation boards can be fitted above the deck during replacement, improving both drainage and thermal performance. This is especially worthwhile during a full flat roof replacement.

Coverage

Flat Roofing — All Locations

Flat Roofing Ely Flat Roofing Newmarket Flat Roofing Huntingdon Flat Roofing Royston Flat Roofing St Ives

Specification

Flat Roof Materials and Standards

We use two flat roofing systems — both proven, both guaranteed, each suited to different applications. EPDM (ethylene propylene diene monomer) is a synthetic rubber membrane manufactured by Firestone or ClassicBond. We use 1.2mm thickness as standard — thicker than the 1.0mm some installers use — because the marginal cost difference gives significantly better puncture resistance and longevity. EPDM is supplied in single sheets up to 15m × 15m, eliminating the joints that are the primary failure point on multi-sheet systems.

GRP (glass reinforced polyester) uses Scott Bader Crystic resin with 450gsm chopped strand mat, finished with a UV-stabilised topcoat. We apply a minimum two-layer laminate — one basecoat layer and one topcoat layer with the matting sandwiched between. Some installers use a single layer to save time and material; we don't, because single-layer GRP is more prone to cracking and has a shorter lifespan.

Deck Specification

The deck beneath the membrane is just as important as the membrane itself. We use 18mm WBP (weather and boil proof) plywood for GRP installations — standard OSB boards flex too much and cause GRP to crack. For EPDM on existing decks, we check board condition, replace any soft or delaminated sections, and ensure all joints are tight before bonding the membrane down. A flat roof is only as good as what's underneath it.

Next Steps

Ready to Get Started?

Getting your roof sorted starts with a single phone call. We answer the phone ourselves — no call centres, no automated menus. Tell us what you need, and we will arrange a free site visit at a time that works for you. During the visit, we inspect the roof in person, take photographs of any issues, and discuss your options face to face. You will receive a detailed written quote within 48 hours — itemised, with materials specified by name and a clear timeline for the work.

There is no pressure to proceed and no obligation. If you decide to go ahead, we schedule the work at a time that suits you and confirm everything in writing. Most repairs are completed within two weeks of booking. Larger projects like re-roofs are typically scheduled 3-4 weeks ahead, depending on the time of year. Call 0122 366 6465 today — we are here to help.

Flat Roofing Cambridge

What Flat Roofing Options Do We Offer in Cambridge?

Flat Roofs Across Cambridge

GRP vs EPDM — Which Is Right?

How We Install Flat Roofs

Deck Inspection

Fall Correction

Membrane Installation

Detailing and Handover

What Our Customers Say

How to Tell You Need Flat Roofing

How a Cambridge Flat Roofing Job Runs

1. Survey

2. Written quote

3. Scheduling

4. The work

5. Cleanup & sign-off

Job Durations at a Glance

Access, Scaffolding & Permits in Cambridge

What Flat Roofing Costs in Cambridge

What moves the price

The Guarantee in Plain Terms

Living Around the Work

Frequently Asked Questions

Flat Roofing — All Locations

Flat Roof Materials and Standards

Deck Specification

Ready to Get Started?

Get Your Free Roofing Quote