EPDM vs Fibreglass vs Felt: Comparing Flat Roof Coverings
Flat roofs aren’t all the same once you look past the surface – the covering material makes a big difference to lifespan, cost and how the roof performs. Here’s how the three most common options compare.
Quick Answer
EPDM rubber offers the best lifespan-to-cost balance for most flat roofs (25-40 years); GRP fibreglass gives a seamless, walk-on-friendly finish at a similar cost; traditional felt is the cheapest upfront but has the shortest realistic lifespan (10-15 years).
EPDM Rubber
A single sheet membrane with very few joints, so fewer potential leak points, and flexible in cold weather. One of the most common choices for garage and extension flat roofs today.
GRP Fibreglass
Laid in liquid form and cured to a rigid, fully seamless surface. Tough underfoot, and a common choice where the roof doubles as a walkway or balcony.
Traditional Felt
The older standard, built up from multiple layers bonded with heat. Cheaper upfront, but seams and edges are the most common failure point, and it has the shortest lifespan of the three.
Flat Roof Coverings Compared
| Material | Typical Lifespan | Best For |
|---|---|---|
| EPDM Rubber | 25 – 40 years | Most domestic flat roofs – durable, minimal maintenance |
| GRP Fibreglass | 25 – 30 years | Roofs that need a seamless, walk-on-friendly surface |
| Traditional Felt | 10 – 15 years | Budget projects or short-term coverage |
Frequently Asked Questions
Can I replace felt with EPDM without a full rebuild?
In most cases yes – the existing deck can usually be reused, with the old felt stripped back before the new membrane is fitted.
Is fibreglass more expensive than EPDM?
They’re broadly similar in cost for most domestic jobs – the right choice usually comes down to whether you need a walkable surface.
Which flat roof covering lasts longest?
EPDM and GRP fibreglass both significantly outlast traditional felt, with EPDM often rated at the top end for minimal-maintenance longevity.
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