Roofing

osb 3 spacing inside parapet wall

Anonymous user 28/02/2024 - 3.52 PM

Hi all, ive built a single story side extension with a parapet wall and im now onto the roof stage. The joists have been installed with firring strips on top giving it a pitch for rain water. When nailing down the first layer of osb 3 sheets before the insulation ect how much of a gap between each osb board should I leave for expansion? Also what size gap should be given around the peremiter where the boards meet the parapet wall? And should I use some kind of split down the centre timber on the peremiter before curling the epdm sheet up the wall? Is it best to stagger the boards or is it ok to lay them side by side in a row? As for drainage what's the best way for me to direct (funnel) the water into the through the wall pipe going into the hopper, bare in mind I've already got a fall going down to the 1 side of the parapet wall. Thanks for the time and sorry for so many questions 👌🏻