OSB boarding

[george765]

I am about to board over a flat roof with OSB3 prior to vapour barrier and insulation. Should I leave a gap between the boards to allow for expansion ? or does the screwing down prevent a problem ?
thanks, George

 

[cotswoldbuilders]

You would have been better of using the t & g osb.
Any gaps in the boards will show through the rubber.

 

[george765]

thanks but as said, I am going over with vapour barrier and insulation before edpm, so gaps wont show. I managed to find the info though........
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OSB FIXING
Provision should be made for possible expansion by allowing for a gap at the rate of 2mm per metre run. A perimeter gap of minimum 10mm should be incorporated. In addition, for square-edged boards, a gap of 3mm should be left around the perimeter of each board.
Boards should ideally be fixed directly to the supporting structure by nailing at 100mm
centres. Length of nails should be at least 2.5 x the board thickness.