What are the best boards for a GRP flat roof


OSB3 Tongue & Groove ( Oriented Strand Board ) is the roof deck of choice for laying a new fibreglass roof. It’s rough textured surface allows the resin to get a firm grip and key into the board, meaning there is very little chance of delamination ( the matting peeling away form the surface of the wood ). With standard square edge boards allow 3mm gaps between adjoining boards for expansion.

When using square edge be prepared to

  • Leave a 3-4mm gap between each board edge (for internal movement and expansion)
  • Vigorously abrade plywood to improve bond with 40-60 grit red aluminium oxide paper
  • Apply masking tape to all joints to prevent resin ingress when the bandage is applied *ensure resin can soak into the tape do not use duck tape this is an old style method,
  • Apply an additional glass bandage (450g x 75mm) prior to the main laminate.
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