Hi Im new to forum so any help greatly appreciated. Plan is to lay 100 pir over ex ground floor felt roof 12'x8' (cracked but not yet leaking), then new osb deck folowed by grp system. Do i need to fix new osb through pir (using long screws into ex joists) as this would seem to stop any expansion taking place? how to prevent uplift etc without fixing down. thanks in advance
The best way is to waterproof glue t&g osb into one monothic fully floating piece, this to avoid any chance of leakage. Then cover with a geotex fabric followed by a one piece made to measure #firestone rubber covering. Then cover with pea shingle, the shingle will hold the roof down and will prevent any ultraviolet damage. This presumes the joists are up to it. The problem with fibreglass is that you cannot be sure of the coverage and cannot see any pin holes, unless you go over it several times and build up to at least a quarter of an inch. While fibreglass may sound good, afterall they make boats out of it, unless you do it yourself and take a lot of care you will probably end up with a rotten roof. (if a boat has a hole you can easily see - with a roof you cannot)
Hi thanks for info sounds like a better option than grp what depth of shingle would be needed ? I would have pref a mechanical method but that will stop expansion? Will that matter with epdm? Seems to be turning into bit of an epic! TIA jg
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