GRP Fibreglass Roofing — North London
Seamless Fibreglass Roofs
That You Can Walk On
For 30 Years or More
GRP fibreglass creates a single, jointless waterproof shell across your entire roof — no seams, no weak points, no maintenance. It's the strongest flat roofing system available for balconies, walkways, and high-use areas.
★ 30–40 year lifespan · Zero seams · Walk-on durable
What Is a GRP Fibreglass Roof?
GRP (Glass Reinforced Plastic) roofing — commonly called fibreglass roofing — is a system where liquid resin is applied over glass fibre matting directly onto the roof deck, curing to form a rigid, completely seamless waterproof shell. Unlike sheet-based systems such as felt or EPDM, GRP has no joints, seams, or overlaps — the entire roof surface is one continuous piece.
This seamless construction makes GRP the most leak-resistant flat roofing system available. It's also exceptionally strong — you can walk on a GRP roof without concern, making it the preferred choice for balconies, roof terraces, walkways, and any flat roof that needs to withstand regular foot traffic.
At AC Roofing & Carpentry Ltd, we install GRP fibreglass roofs on extensions, balconies, dormers, garages, and commercial buildings across North London. Each installation is laid up by hand on site using high-quality polyester resin and chopped strand matting, with a pigmented topcoat that provides UV resistance and can be colour-matched to your property.
GRP is a premium system with a lifespan of 30–40 years. For properties where durability, walkability, and zero maintenance are priorities, it's the best flat roofing investment you can make.
Real Work
See Our Fibreglass Roofs Projects
Why Alternative Systems Fall Short on High-Use Roofs
Traditional flat roofing materials — felt, single-ply membranes, even EPDM rubber — all rely on sheet materials with joints and overlaps. Every joint is a potential failure point. Over time, adhesives degrade, seam tape lifts, and the weakest point of the roof becomes the first to leak.
If your flat roof doubles as a balcony, terrace, or walkway, the problem is compounded. Foot traffic stresses sheet membranes at the seams, accelerating wear. Furniture and planters create point loads that can indent and damage softer materials. Impact from dropped items can puncture single-ply systems.
We regularly replace felt and single-ply roofs on balconies and terraces across North London that failed within 5–10 years because the material simply wasn't designed for foot traffic. The homeowner pays twice — once for the original installation and again for the GRP replacement they should have had from the start.
GRP eliminates all of these failure modes. There are no seams to split, no adhesive to fail, and the cured laminate is strong enough to drive a vehicle across. If you're investing in a flat roof that needs to perform under load, GRP is the only system that makes financial sense over the long term.
How We Work
Our GRP Installation Process
Survey & Design
We measure the roof, assess falls, and design the drainage layout.
Deck Preparation
Plywood deck fitted or existing deck cleaned, dried, and prepared.
Laminating
Resin and glass fibre matting applied by hand, building up the waterproof shell.
Topcoat & Trim
Pigmented topcoat applied with edge trims and drip details installed.
Cure & Handover
Full cure verified, clean-up completed, and written guarantee issued.
Why It Matters
Why GRP Is the Premium Flat Roof Choice
Completely Seamless
No joints, seams, or overlaps — zero potential leak points.
Walk-On Durable
Strong enough for regular foot traffic, furniture, and planters.
30–40 Year Lifespan
One of the longest-lasting flat roofing systems available.
Colour Matched
Topcoat available in any RAL colour to complement your property.
Zero Maintenance
No recoating, resealing, or treatment required. Clean occasionally and that's it.
Impact Resistant
The rigid laminate resists puncture, impact, and point loading.
GRP Fibreglass Roofing: Materials and Specifications
The Laminating Process
GRP roofing is laid up in layers — similar to boat building. A catalysed polyester resin is applied to the prepared deck, then 450g/m² chopped strand glass fibre matting is embedded into the wet resin. The matting saturates with resin, and once cured, forms a rigid composite laminate that's both waterproof and structurally strong. On standard roofs, a single layer of matting is sufficient. For high-traffic areas or larger roofs, a double layer provides additional strength and puncture resistance.
Topcoat and Finish
The topcoat is a pigmented, UV-stabilised polyester resin that provides the finished appearance and weather protection. It's available in a wide range of RAL colours — from standard grey and green to bespoke colours matched to your property. The topcoat includes a non-slip aggregate for walkway applications. A properly applied topcoat lasts 15–20 years before needing a refresh — and refreshing it simply involves cleaning and applying a new coat, which costs a fraction of a full replacement.
Deck and Substrate Requirements
GRP must be applied to a rigid, stable substrate — typically 18mm WBP plywood. OSB is not recommended because its surface texture can cause adhesion issues with the resin. The deck must be clean, dry, and free of any contaminants. For new builds or extensions, the plywood deck is fitted over timber joists with falls built into the structure. For re-covers, the existing deck is assessed — if sound, it can be overlaid with plywood; if damaged, it's replaced.
GRP vs EPDM: Which Is Right for You?
GRP and EPDM are both premium flat roofing systems, but they serve different needs. EPDM is a flexible rubber membrane — lightweight, easy to install, and cost-effective for straightforward flat roofs. GRP is a rigid composite — stronger, walked-on durable, and seamless. If your flat roof won't see foot traffic and you want the most cost-effective premium option, EPDM is the right choice. If you need walkability, impact resistance, or a seamless finish, GRP wins. We install both systems and recommend based on your specific requirements.
Residential vs Commercial GRP
GRP is used extensively in both residential and commercial applications. Residential installations typically cover extensions, balconies, dormers, and garage roofs. Commercial applications include walkway roofs, plant room enclosures, and flat roofs on retail or office buildings. For commercial projects, we can specify fire-rated GRP systems that meet the fire performance requirements of Building Regulations Part B.
Common Questions
Frequently Asked Questions
Protect Your Property Today
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