If you’re deciding between EPDM roofing vs GRP flat roofing for a garage, extension, or balcony in Weston-super-Mare or North Somerset, this locally focused guide provides everything you need. We cover real-world performance, average installation costs, durability in coastal conditions, and best-fit scenarios. Whether you’re in Clevedon, Portishead, or the wider North Somerset area, this article is tailored to help you make an informed roofing decision.
As local flat roofing specialists, we install, repair, and maintain both EPDM and GRP systems with proven experience across Somerset’s coastal towns and inland villages. Let’s dive into the key differences and what really works best near the sea.
🔍 What is EPDM Roofing?
EPDM stands for Ethylene Propylene Diene Monomer—a durable, synthetic rubber roofing membrane used widely for flat roofs. It’s laid in large sheets with minimal seams, making it ideal for simple roof shapes like garages or modern extensions.
✅ EPDM Roofing Pros:
- Long service life: 20–30+ years
- Minimal seams = fewer leak risks
- High resistance to UV, ozone, and temperature fluctuations
- Perfect for larger, straightforward roof designs
- Low maintenance and lightweight
⚠️ EPDM Considerations:
- Needs a solid roof deck and correct adhesives/primers
- Not a load-bearing surface without protection layers
- Intricate detailing (e.g. skylights) needs an experienced installer
🔍 What is GRP Roofing?
GRP (Glass Reinforced Plastic), also known as fibreglass roofing, is a liquid-applied system. It cures into a hard, seamless, waterproof layer—making it excellent for roofs with tricky details like corners, trims, and upstands.
✅ GRP Roofing Pros:
- Seamless, watertight, and rigid finish
- Ideal for smaller, complex roofs (e.g. bay windows, porches)
- Easily shaped around rooflights, pipes, and parapets
- Crisp, clean edge detailing
⚠️ GRP Considerations:
- Installation requires dry, mild weather
- Incorrect resin ratios can lead to blistering or cracking
- Rigid finish may craze with movement if expansion joints are missed
💷 Flat Roof Costs in Weston-super-Mare & North Somerset (Installed Prices)
| Roofing System | Average Cost (per m² installed) | Notes |
|---|---|---|
| EPDM | £90 – £130 | Simpler installation, ideal for larger areas |
| GRP | £110 – £160 | Price affected by trims, curing weather, detailing |
👉 Factors Affecting Cost:
- Roof size & complexity
- Access/scaffolding needs
- Warm roof vs cold roof insulation build-up
- Edge trims and skylight detailing
📍 For a personalised quote, get a free roofing survey here.
⏳ Lifespan & Warranty Expectations
Both EPDM and GRP roofs offer excellent longevity when installed correctly:
- EPDM Roofing Lifespan: 20–30+ years
- GRP Roofing Lifespan: 20–25+ years (requires proper expansion detailing)
💡 Pro Tip: Annual inspections and proactive roof maintenance extend the life of your roof and keep manufacturer warranties valid.
🏡 Best Roofing System by Use Case
| Roof Type | Best Option | Why? |
|---|---|---|
| Garage Roofs | EPDM | Cost-effective and quick to install |
| Bay Windows/Porches | GRP | Superior detailing and crisp finish |
| Balconies & Terraces | EPDM or GRP | Add slip-resistant finishes for foot traffic |
| House Extensions | Depends | Consider insulation, skylights, edge aesthetics |
👉 Explore our Flat Roofing services in Weston-super-Mare for tailored advice.
Warm Roof vs Cold Roof Build-Up
Understanding the insulation method is essential to long-term performance:
Warm Roof:
- Insulation installed above the deck
- Minimises condensation risk
- Increases build-up height slightly
Cold Roof:
- Insulation at ceiling level
- Requires through-ventilation to avoid damp issues
During surveys, we check soffit ventilation, cross-airflow, and signs of internal moisture to advise on the best build-up.
Common EPDM & GRP Roofing Issues We Fix in North Somerset
Typical EPDM Roofing Problems:
- Poor bonding at upstands or corners
- Punctures from tools or foot traffic
- Leaks from under-spec’d flashings
Common GRP Roofing Failures:
- Pinholes in resin coat
- Alligatoring from poor thermal detailing
- Ponding due to bad falls or trapped moisture
👨🔧 Read our latest Roofing Maintenance Guides to see how we solve these issues locally.
Roofing on the Coast: Why Detailing Matters in Weston-super-Mare
Salt-laden air and high winds are unique challenges in coastal areas like Weston, Clevedon, and Portishead. We always specify:
- Mechanical edge fixings for storm resilience
- Correct drip trims to control water runoff
- Lead or proprietary flashings for longevity
- Expansion joints in GRP systems on larger surfaces
When Should You Replace vs Re-Cover a Flat Roof?
We’ll assess your existing roof deck (usually OSB3 or ply). If it’s swollen, delaminated, or soft from trapped moisture, we recommend a full deck replacement rather than just re-covering.
✅ We always aim for 1:80 minimum falls to reduce ponding and water pooling.
EPDM vs GRP Roofing FAQs (Weston-super-Mare)
Q: Which is cheaper for a typical garage roof in Weston-super-Mare?
A: EPDM is usually more cost-effective and faster to install, especially on simple, rectangular roofs.
Q: Is GRP stronger than EPDM?
A: GRP is more rigid and great for detailed work; EPDM is more flexible, better for larger or moving structures. Strength depends on your use case.
Q: Can I walk on my flat roof?
A: Only if the roof is specified for foot traffic. For EPDM, we add walkway tiles. For GRP, we apply slip-resistant topcoats.
Q: How fast can you install a flat roof?
A: Simple roofs can be completed in a single day once access is arranged. Complex shapes or poor weather may extend install time.
Q: Do you cover Clevedon and Portishead?
A: Absolutely. We serve all areas in North Somerset: Clevedon, Portishead, Yatton, Congresbury, Winscombe, Cheddar, and beyond.
📘 See all service areas on our About page
Local Roofing Expertise You Can Trust
Whether you’re replacing an old roof or designing a new one, RMoss Roofing WSM offers free consultations and detailed advice tailored to your specific home and location.
We provide:
- 🏠 Flat Roof Installation & Repairs
- 🏠 Pitched Roof Maintenance & Replacement
- 🛠️ Storm Damage Roof Repairs
- 🧰 Emergency Call-outs
- 🧱 Chimney Repairs, Lead Flashing & Gutters
Areas We Serve
We provide roofing services across:
- Weston-super-Mare
- Worle
- Portishead
- Cheddar
- Clevedon
- Congresbury
- Burnham-on-Sea
- All surrounding North Somerset villages
Book a Free Consultation with RMoss Roofing WSM
Need expert advice for your home roofing project in North Somerset? Whether you’re leaning towards a modern flat roof or a traditional pitched roof, we’re here to guide you with honest recommendations and professional service.