Flat roof dilemma

[Dan77]

I have a fibreglass flat roof and need to bring the flue for my new boiler out through it
My plumber is not prepared to do the waterproofing around the penetration as he has never done this with GRP before so it’s down to me to try and sort it
My question is what is the best pipe collar/flat roof slate to use on a fibreglass roof?
Can’t seem to find much on tinternet

 

[vinty]

I did a GRP roofing course with a company called Polyroof in flintshire Wales ,they sell GRP components for GRP Roofs, edge trims and pipe collars ect.
They will post them to you with instructions.
The pipe Collars are made of GRP ,they are slipped over the pipe and then glassed to the roof.