Plywood under Corrugated sheeting

mengele

Have an old smallish garage that I need to re-roof on a farm. It has corrugated sheeting on it that is red rotten. I have a lot of new 1 inch plywood left over from another job. How would the following work as providing a small bit of insulation and more importantly decreasing condensation?

The roof has 4 timber a frames with timber purlins then crossing. I am thinking of screwing in the plywood first onto the purlins. then a layer of damp proof membrane and then the corrugated sheeting (its bought already and is Tegral 0.6mm).

Would this do anything in stopping condensation for those muggy winter days? Im living by the coast so get foggy damp weather quiet often.

Lumen

I would use a breathable membrane and then battens under the corrugated sheeting to create a cavity, and ventilate that at the eaves and ridge.

That way you have good air flow which should keep both the roof timbers/ply and underside of the sheeting dry in winter, and it'll also prevent overheating of the interior in summer as the heat can escape from under the sheeting.