OSB on flat roof.

[Gilesda]

Hi all.
Using 18mm tongue and groove OSB on a flat roof. Do the end joins need to be over a joist? Or are the tongue and groove joints ok if they are between two spans?
Also are the joints, length and width, normally glued?
Thanks.

 

[oldbutnotdead]

Long as the end joins are t & g then no they don't need to be on a joist. Best to stagger the end joins (lay the boards in a brick bond). PVA in the joints won't hurt, i've never bothered (usually as the deck for grp) but do use lots of decent big screws (you want 40mm going into the joists at 200 centres) if using grp. Felt or rubber cover less critical on fixings...