I need advice on flat roof replacement. A cowboy builder built a fibre glass flat roof with Velux window and incorrect slope about 6 months ago. The problem I am having with the roof is minor leaking especially around eaves and Velux due to incorrect slope and job was done poorly.
Recently a roofer suggest following:
Option 1: Rip off existing roof, correct slope and change Velux window to roof dome and redo fibre glass.
Option 2: . Re do a new structure timber deck roof to 15 degrees pitch roof. Apply 18mm osb board and GRP fibreglass system with a top coat in grey. Sides of the extension timber deck it and supply a plastic fascia board
Which option would be better? Can someone please advise me?
On looking, both options are pretty much the same. I would rip it all off and start again with a minimum fall of ½ an inch per 12 inches of run. IE 1 in 24. The minimum recommended by Building Regulations is 1 in 40.
I would use 3mm rubber rather than GRP as it’s guaranteed for 40 years and will move if the roof moves, which they always do.
Both options would work. In this case, it is all about getting the correct slope. Once you have that right everything else should be fine. If I had to choose an option well then option 2 would be what I would go for. It's more comprehensive.