Grp to felt roof

Wouldn’t know never done this before, a point to note GRP is fire retardant but not fire proof and will bubble up and burn how will this react with the GRP is anybody guess maybe ring up the manufacture and ask for there opinion and advise? Also might be worth making a small mock up to test how it will react ? But honestly GRP isn’t that hard to strip just get a floor scrapper under it and it will pull off failing that work out where the boards are use a angle grinder to cut the GRP and just take the boards up with it still on there be very heavy though you could try using a Circular saw to cut into more manageable sections? Also you can use a angel grinder with a stone grinding blade or general diamond cutting blade or to be honest any blade if your using a abrasive disk don’t push too hard as there disk will snap and possibly cause serious injury Ive made this mistake that why I just use metal cutting or grinding disks now as the chase of it exploding like that is slimmer you can use this technique to grinder down the GRP if there huge bubbles in it much quicker then sanding it down you can also use it this method to quickly key up the surface if lets say you wanna repair a cracked GRP roof and can’t be bothered to sand the top layer off for instance. Hope this helps regards Frankie BT Roofing Services

Hi I defo would not I would strip the grp first

It’s always advised to remove any old roof materials before applying new.

Felt can only be applied directly onto a solid, sound timber base as the base layer needs to be fixed to the boarding, under no circumstances should felt be torched onto a GRP Resin roof Ian Marks

This would definitely be bad practice. The heat from the torch would melt the GRP, regardless of the primer. The GRP would need removing, boards below checked and actioned accordingly, primed, and torch on felt system applied.

Yes bitumen primer as long as the decking is not rotten under the grp

This would be a bad idea and definitely not recommended as my guess would be it would react but even more importantly felt roofs should go down in 3 layers and the bottom 2 are the important ones if the first layer isn’t correctly fitted to wooden base it will lift over time and cause bubbles and the second is your main water barrier with the 3rd being a mineral finish for a nice finish and protection against the elements hope this helps

In the first instance, the grp roof should have a 10 year guarantee as standard but i wouldnt recommend putting felt on top of grp. I would only install felt onto a clean deck to insure any new work done.