Questions & Answers


When do I need to use expansion joints

I read online that I was supposed to use expansion joints on large fibreglass roofs but the contractor I found in the local trade mag told me I didn't need to worry about it.

The size of the roof I want to use GRP roofing materials on is approx 60 square metres and almost square in shape. Would I need to use expansion joints on this roof?


The inclusion of expansion joints on a GRP flat roof depends on a number of different factors and should be explained to you at the site survey stage. The general rule of thumb is that anything over 50 square metres needs expansion joints.

Using expansion joints with GRP roofing can depend on the shape of the roof and if the surface includes skylights or other roof furniture, however in your case without seeing the roof and going off the information you've provided above I would recommend expansion joints be fitted.

GRP Roofing is a super strong material, but it doesn't flex that much so on large roofs like yours, you need the joints to aid with thermal expansion and contraction.