Revisions log for Answer #2054

When laying without purlins, the thickness of the osb should be bigger. So it is cheaper and more convenient to lay osb on the purlins.

Lay with a gap of 3 mm – summer, 5 mm – autumn, winter, spring.

Purlins are laid across the rafters, along the rafters are nailed counter-battens, which makes the air gap.