Installation of fibreglass roofing has been described as technical, the recent years have seen a huge change in its description with a fair few people completing their own work as DIY projects. By following preparations, guides and watching youtube videos Joe Blogg can even complete hitch-free and successful installation.

Let’s quickly highlight the installation processes:


Roof preparation to receive fibreglass: Fibreglass roofing installation is carried out by first preparing the decking. This is done by removing all the unwanted substances related to old decking, ensuring that the roofing joists are cleaned and cleared of lots in readiness to receive fibreglass. All the conditions specified ensure the decking is dry and free of moisture, this must be met to avoid fiberglass failure. The correct boards must be used based on the application areas. The boards are laid 90o lengthways to the roof support to form the base. The fibreglass flat roofing mainly depends on the correct laying of the deck as incorrect or faulty deck preparation can affect the quality of the fibreglass installation. Composite Roof Supplies recommends using OSB for best results.

Joining of roofing members: The boards are nailed to the timber supports with the use of a compressed gas or air-powered nail gun to reduce any damage and at the same time for roofing rigidity. After driving nails into the joists, the edge trims will then be nailed with the help of screw gun or hammer or stapled to the decking board with the use of applicant called Polyurethane adhesive. After the joints trimming, the platform is now ready to receive lamination.


Roof lamination: This process involves mixtures of resin in a correct proportion before applying it on the mat to cover all the corners. It is important to use correct resin ratio to glass. However, the recommended rate is to apply one-third resin and two-thirds glass to the board and mat respectively in the process of laying the main laminate. This will finally give resin-coated deck and transparent finished laminate.

Final application: The laminate is allowed to dry, and the top-coated resin is then added with the required amount of catalyst mixtures applied thinly to avoid crack. You can find Catalyst ratio charts on the catalyst container from your Composite Roof Supplies kit.

In summary:

  • Clearing of the existing felt or any existing roofing substances to expose the roof joists.
  • Make sure poor water drainage is corrected typically with timber firing.
  • Adjust the deck area if need be to 18mm external gradient.
  • Fixing of flashing trims, edging trims, and fillets trims which have been especially pre-moulded are required.
  • Forming of seamless membrane by applying cut to size matting and coated resin on the deck.
  • Application of top coated resin to the roof after curing.
  • Installation of GRP or lead flashing at the roof wall.
  • The GRP roof is then extended towards the tile roof base.
  • Lastly, all the waste and unused substances are removed from the site.

However, the boards’ temperature is very crucial, if you are in doubt in laying your fibreglass roofing, Composite Roof Supplies is one of the prominent roofing suppliers and will always endeavour to help as much as possible.

Contact CRS:
Tel: 0207 101 3977