Fibreglass (GRP) roofs

GRP roofs do expand and contract a lot in different conditions compared to other roof coverings. As long as the sub decks and fixings are used correctly you will not get this issue. *Making sure gaps are left where boards meet property walls are crucial. *Expansion gaps on roofs over 50sqm. *Use OSB tounge and groove boards for sub deck and top deck. *Do as a warm roof if no height restriction. *Use two layers of PIR insulation staggered to create the build up instead of one thick sheet. GRP roofs are an excellent when installed correctly. Most problems occur from poor installation or using low cost materials.

EDPM is the solution as the rubber will give as the roof expands and contracts. Things to note are best to install new OSB and check the fall of the roof. Then the facias might need changing aswell as you will have a gap where the old felt lipped over

For such a small area maybe it would be better to use Firestone EPDM rubber roof system it’s better than a standard GRP roof With fibreglass if the mixture is not done to the right temperature then within 12 to 18 months holes and cracking can appear Advice would be read the pros and cons between the two

Hi Not a great fan of fiberglass roofs to be fair. If it’s only 2.5 metres would recommend a rubber single ply Alvitra system. Or if you wanted to go better if the roof could the weight can be done in lead and would last a lot longer than felt, fiberglass, firestone, single ply if fitted correctly.

As a roofing contractor and an approved Restec Flexitec installer, I’d happily recommend a high-quality GRP system for a roof of this size. When installed correctly, GRP shouldn’t be making constant cracking or popping noises. Like any roofing material, it will expand and contract slightly with changes in temperature, but on a properly constructed roof with the correct decking, expansion detailing and installation methods, it’s generally not something homeowners notice. One of the biggest advantages of a modern GRP system such as Restec Flexitec is that it’s completely seamless, so there are no joints for water to penetrate. It’s also highly durable, UV resistant, maintenance-friendly and far less prone to the issues you can get with ageing felt roofs, such as splits, blistering and failed laps. Another benefit of the Restec Flexitec system is that it can often be installed over suitable existing substrates (subject to a moisture test), reducing disruption while still providing an extremely robust waterproof finish. As an approved installer, every installation is completed to the manufacturer’s specification and can be registered for the manufacturer’s guarantee, alongside my own workmanship guarantee. For a small 2.5m² flat roof over a window, I’d choose GRP over traditional felt every time. It will give you a clean, modern finish with a much longer expected service life, and if it’s installed correctly, noise from thermal movement shouldn’t be a concern. As with any roofing system, the quality of the installation is just as important as the material itself.