Noises coming from my GRP roof

Loud banging or cracking noises can be heard coming from the GRP roof

Possible causes

Loud banging and cracking noises coming from your GRP fibreglass roof could be for a number of different reasons which we list below.

Thermal expansion and contraction

When a roof heats up and cools down during the course of a day, it will make noise, this is due to thermal expansion and contraction and is a completely normal process.

If a flexible GRP roofing system like Fibrelast was used, then the entire system will flex. For roofs over a certain size, special expansion joints are added to help with flexibility.


This can be caused by a wide range of problems including applying the materials on roof decking not specified for use with the system (ie plywood or chipboard instead of OSB3), damp roof deck at the time of lamination or incorrect catalyst ratios.

Trim issue

Incorrectly fixed Loose GRP roofing trims grinding up against an upstand, flashing or large trims overlapping one another could make a small cracking noise.


Unfortunately, loud banging and cracking noises could be a number of different things and not possible to recommend a quick solution.

If you've had the GRP roof installed by a professional contractor then take the issue up with them, they may come out and investigate further and solve any issues there may be.

If this was a DIY project then you'll need to get up on the roof and troubleshoot any problems yourself. Check for any visual cracks in the trims or roof surface and make sure that the decking was laid in accordance with the system guidelines.