GRP / EPDM or other

Im currently quoting for an orangery flat roof with lanterns.

Usually we do GRP but this roof is bigger than usual, its 70 sq metres (about 3.6m wide in a U shape).

Im wondering due to the size whether a flexible roof system, like EPDM or liquid roof, would be better than GRP on this occasion.

 

Bear in mind fitting epdm where lanterns are involved is a ball ache when it comes to flashing up the lantern kerb and the corners. Personally I think epdm is best suited for a plain sided roof. If you do fit epdm then board the hole where the lantern will be so the rubber doesn’t sag down and pull when you fit it. You can cut the home out and remove the board afterwards.

 

Cut the hole out

 

You could look into using a fibre reinforced polyurethane liquid applied system, which would be applied in roughly the same way as a traditional GRP roof using a 225gm mat instead of 450 or 600gm. Polyurethane systems are really easy to apply and incredibly flexible so you wouldn't have any issues with thermal expansion.