A quick comparison of fibreglass vs felt roofing—discover which flat roof lasts longer, performs better, and offers the best long-term value.
Why More Homeowners Are Choosing Fibreglass
When deciding between a felt roof and a fibreglass (GRP) roof, most homeowners quickly discover that fibreglass delivers far better performance, longevity, and overall value. Felt has been around for decades, but fibreglass has become the modern standard for anyone wanting a roof that looks better, lasts longer, and requires far less maintenance. At Fibre-Form, we install GRP systems every single day — and the difference between the materials is clear.
Seamless vs Seamed Roofing
One of the biggest advantages of fibreglass is its seamless design.
Felt roofing relies on multiple sheets and heat-welded joins which are the first parts to fail, crack, or lift. Over time, these weak points allow water to penetrate.
Fibreglass is applied as one continuous waterproof surface with no joins, meaning no weak spots and a dramatically lower risk of leaks. A well-installed GRP system becomes a single, solid membrane that remains watertight for decades.
Lifespan and Long-Term Reliability
A properly installed fibreglass roof can last 30–40+ years, while felt roofs often struggle to reach even 10–15 years without issues. Felt commonly needs repairs long before the end of its expected life.
Fibreglass performs better in the long run because it resists:
Blistering
Cracking
UV damage
Moisture absorption
This makes GRP significantly more cost-effective over its lifetime.
Strength and Durability
Felt roofs can become brittle, soft, or deformed under heat, cold, and heavy weathering. Fibreglass forms a rigid, impact-resistant shell once cured, making it ideal for:
Extensions
Garages
Commercial roofs
Balconies & terraces
Walkways
At Fibre-Form, we use the newest flexible fibreglass materials designed to move naturally with the building, preventing cracks and ensuring long-term durability.
The Truth About “Fibreglass Cracking”
Many people believe fibreglass roofs crack — but this only happens when installed by poorly trained, one-day-course roofers using the wrong materials and techniques.
Fibreglass itself does not fail when installed correctly.
At Fibre-Form, fibreglass is all we do. Our installers specialise exclusively in GRP roofing systems, applying techniques perfected over years of experience. When GRP roofs crack, it’s not the material — it’s the installer.
A Cleaner, More Modern Finish
Felt roofs often look uneven, patched, and dated. Fibreglass delivers a clean, modern, high-end finish that instantly improves the appearance of any property. It can also be coloured, textured, or coated with anti-slip finishes, making it far more versatile — especially for balconies and outdoor spaces.
Fire Safety Advantages
Modern fibreglass roofing systems can be fully fire-retardant, offering a level of protection felt cannot always match. This makes GRP an excellent choice for both residential and commercial applications where safety matters.
More Overlay Options
Fibreglass can often be installed directly over existing felt, saving time, cost, and disruption. We also specialise in overlaying failed fibreglass roofs installed by inexperienced contractors, restoring them to the quality they should have had from the start.
The Clear Winner
When considering lifespan, appearance, strength, waterproofing, and long-term performance, fibreglass is the superior system in almost every category. While felt may be cheaper upfront, it simply cannot compete with what GRP offers.
For homeowners and businesses wanting a roof that will stand the test of time, fibreglass remains the strongest, smartest, and most modern choice.
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