When I built my ridge roof with an air gap, I attached hardboard on top of the rafters, then nailed about 3 cm battens on top of the hardboard, and then the roof decking. That means the insulation is against the hardboard on the inside, and the air gap is between the hardboard and the roof decking.
A simple and quick solution in my opinion, with minimal cutting in the hardboard. This assumes, of course, that you are rebuilding the entire roof and not just opening up to the attic...
No water should enter the air gap, so the most important thing in material choice is that it is stable enough so the insulation doesn't "press" away the air gap.
Good luck
A simple and quick solution in my opinion, with minimal cutting in the hardboard. This assumes, of course, that you are rebuilding the entire roof and not just opening up to the attic...
No water should enter the air gap, so the most important thing in material choice is that it is stable enough so the insulation doesn't "press" away the air gap.
Good luck