Lee FlecknellEmergency roof repairs, rental property · August 2026
Highly recommend this company carried out some emergency roof repairs on one of my properties would use again.
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GRP fibreglass flat roofs
GRP fibreglass roofing for extensions, dormers and balconies
GRP fibreglass roofing gives an extension, dormer or balcony a hard, joint-free surface that is laid in place and cures into one piece. Best Top Roofing lays GRP on new decking with moulded trims and a coloured topcoat, and it is the system we recommend wherever a flat roof will be walked on or has a lot of corners and upstands.
GRP stands for glass reinforced plastic. Chopped strand glass mat is laid on the deck and wetted out with resin, then rolled to remove air so the mat and resin bond into a single laminate. When it cures it is rigid, strong and completely joint-free, including up the walls and around the edges. The photograph at the top of this page shows a roof at exactly that stage, before the topcoat went on.
A GRP roof starts with a good deck, usually new OSB3 boards with the joints taped, because resin will not forgive a deck that moves. We fit GRP edge trims before the laminate goes down so the trims are bonded in, not stuck on afterwards, then apply the laminate and finish with a pigmented topcoat, most often grey. The finished roof is hard wearing enough to take foot traffic, which is why GRP is the right choice for balconies, roof terraces and any flat roof you step onto from a window or door.
GRP needs dry weather and the right temperature to cure, so it is planned around the forecast. Done in the right conditions, it is one of the longest-lasting flat roofs you can buy.
When you call, you speak to the familyBest Top Roofing is family-run. The family that answers the phone and gives you the quote is the family that turns up and does the job.
What is included
- Old roof stripped back to the joists where needed
- New OSB3 decking, joints taped and prepared
- GRP edge trims and drip trims bonded into the roof
- Glass mat laminated in resin and rolled out
- Upstands, corners and outlets formed in the same laminate
- Pigmented topcoat finish, grey as standard
- Non-slip finish for balconies and walkways on request
Signs you need this
- A balcony or terrace that leaks into the room below
- Felt flat roof on a dormer with lots of corners and upstands
- A flat roof you need to walk on for access or maintenance
- Cracked joints around rooflights and roof lanterns
- An extension roof you want to look crisp from upstairs windows
How it works
Survey and deck check
We look at how the roof is used, the deck and every detail.
Fixed written price
Decking, trims, laminate and topcoat set out in writing.
Re-deck and trim
New boards laid and taped, trims fitted to the edges.
Laminate and topcoat
Laid in dry weather, left to cure, then topcoated and inspected.
GRP is laid, not stuck together. With no seams and bonded trims, there are no joints for water to find, and the surface is tough enough to walk on.
GRP fibreglass roofing: your questions answered
How long does GRP roofing last?
A GRP roof laid on a sound deck in the right conditions lasts for decades. The topcoat can be refreshed later in its life if you want to renew the finish.
Can GRP be used on a balcony?
Yes. It is the system we recommend for balconies and roof terraces because the cured surface is hard wearing, and we can add a non-slip finish to the topcoat.
What colour is a GRP roof?
Grey is the most popular topcoat, but other colours are available. The topcoat gives the roof its final look and protects the laminate below.
Why does GRP need dry weather?
The resin must cure without moisture on the deck or rain on the surface. We watch the forecast and plan the laminate day, so the roof is laid in the right conditions.
Is GRP better than EPDM?
Neither is better for every roof. GRP is best where the roof is walked on or has lots of detail; EPDM is ideal for garages and simple extensions. See our EPDM vs GRP guide.
Related services
Reviews
What customers say on Google
Dannie SmithQuoted the next day · June 2026
Thomas came and gave me a quote next day, very professional and clean work was carried out. I will be using best top roofing for all my projects going forward and would highly recommend them.
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R Vidya RLeaking felt roof repaired · September 2026
thanks to Thomas for fixing our roof. It was pleasure working with you. I feel confident that the water leak is accessed from all points and all problem addressed
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Lee SextonNew flat roof · April 2026
I needed a new flat roofing doing and this amazing company did it exactly how I wanted it. Highly recommended. Friendly and polite. Would use and again and tell all my friends and family.
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Mahmoud Al SuwwanRoof problem fixed · August 2026
We had a problem in our roof we called this company and they solved the problem so happy and satisfied. I really highly recommend if anyone needs roofing work done if I ever need a roofer again hopefully we don't if I ever did I will always use this company again, thank you so much, guys.
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Lisa DunneBlocked gutters cleared · April 2026
Cleaned out our gutters as were blocked and overflowing. Very happy with the job done. Thank you very much!
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Ligita KaledaiteChosen over other quotes · July 2026
Very friendly. Had couple of Quotes from other companys And this was the best company for it.
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Sally MaskellRoofing work by Thomas · June 2026
Very impressed with the work that Thomas has done. Definitely recommend.
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Scarlet BullRoofing work · August 2026
Professional, good quality work! Recommended.
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Checkatrade customerBalcony roof installation · August 2026
Fantastic, professional and polite throughout the job.
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10 year
re-roof
guarantee
Our guarantee
re-roof
guarantee
Every new re-roof guaranteed for 10 years, in writing
When we replace your roof, our workmanship is guaranteed for 10 years from the day we finish, and the membrane, tiles and slates carry their manufacturers' guarantees on top. Repairs and flat roofs are guaranteed too, with the terms for your job written on your quote. We are fully insured.
Covered
- Our workmanship on every new re-roof for 10 years
- Lead, flashings, ridges and verges we fit
- Flat roofs laid to the system's specification
- Repairs, with the terms written on the quote
On top
- Tile and slate manufacturer guarantees
- Membrane and flat roof system guarantees
- Photos of the finished job
- The same family to call if anything is wrong
Not covered
- Storm or accidental damage after completion
- Work altered or added by someone else
- Parts of the roof we did not work on
- Gutters left to block and overflow
The guarantee for your job is written on your quote before you agree to anything. Read the full guarantee.
Talk to us about grp fibreglass roofing
Ring or send the form. We come out, look at the roof, show you what is needed and give you a fixed written price. No pressure and no hidden extras.