The Three Main Flat Roof Systems
Modern flat roofing uses three primary membrane systems: EPDM (ethylene propylene diene monomer) rubber, GRP (glass-reinforced polyester) fibreglass, and torch-on felt. Each has specific strengths, limitations, and ideal applications.
The right choice depends on your roof size, shape, usage, budget, and how long you plan to keep the property. Here's how they compare across every factor that matters.
EPDM Rubber Roofing
EPDM is a synthetic rubber membrane installed in a single sheet, bonded to the roof deck with adhesive. It's the newest of the three systems and has rapidly become the most popular for residential flat roofs.
Pros: 50-year material warranty. Single-piece installation eliminates seam failures. Excellent flexibility — handles building movement without cracking. UV resistant. Low maintenance. Lightweight.
Cons: Requires precise installation around upstands and edges. Limited colour options (black or grey). Can be punctured if walked on with sharp objects. Repairs require specialist adhesive patches.
Typical cost: £60–£90 per m² installed. Best for: Garages, extensions, dormer roofs, and any flat roof where longevity is the priority.
GRP Fibreglass Roofing
GRP is a rigid fibreglass system applied in liquid form over a reinforcing mat, creating a seamless, jointless surface. It cures to a hard, durable finish that can be walked on.
Pros: Completely seamless — no joints or seams to fail. Extremely hard-wearing surface. Can be walked on regularly (ideal for balconies). Available in multiple colours and finishes. Fire resistant.
Cons: More expensive than EPDM or felt. Rigid — can crack if the roof deck moves significantly. Requires dry installation conditions. Repairs need professional application.
Typical cost: £80–£120 per m² installed. Best for: Balconies, walkable roofs, bay window roofs, and properties where the roof is visible from above.
Torch-On Felt Roofing
Three-layer torch-on felt is the traditional flat roofing system, using layers of modified bitumen felt bonded together with heat. It's been the industry standard for decades and remains a reliable, cost-effective option.
Pros: Lowest upfront cost. Proven track record over 40+ years. Easy to repair. Multiple layers provide redundancy. Can be installed in most weather conditions.
Cons: Shorter lifespan (15–20 years). Seams can fail over time. Less aesthetically appealing. Requires regular maintenance. Open flame during installation (fire risk on timber buildings).
Typical cost: £45–£65 per m² installed. Best for: Budget-conscious projects, temporary buildings, and roofs that will be replaced within 15 years.
Our Recommendation
For most North London residential properties, we recommend EPDM rubber. It offers the best balance of cost, longevity, and reliability. The 50-year material warranty means you'll likely never need to replace it again.
For walkable areas, balconies, and visible roofs, GRP fibreglass is the superior choice — its hard finish handles foot traffic and looks clean for decades.
We still install felt systems where budget is the primary constraint or the property is due for redevelopment. But for any roof you want to last, EPDM or GRP is the investment worth making.
Every free inspection includes a material recommendation specific to your roof. We'll explain why we're suggesting each system and give you a clear cost comparison so you can decide with confidence.