Welcome! / Forums / General Woodworking Discussions / Projects / My Workshop
Ok, I’m about ready to tackle my roof. So, as final clarification, which of the three configurations in the attached pic is the best to reduce condensation/moisture buildup?
If it matters, I will be cutting vents into the sides of the fascia and those vents will be level with the gaps between the joists where the insulation panels will be located.
Thanks all.
I think that C is what is termed a cold roof – this doesn’t mean that it is less well insulated than what is termed a warm roof but each one has the layers in a slightly different order.A is almost what is called a warm roof but normally the insulation is placed above a timber deck that is on the rafters not next to the underside as you have shown.
So out of the three I would go for A but don’t forget to install a vapour barrier before the plasterboard.
A Warm roof potentially has a slightly better insulating property as the insulation isn’t broken in to sections by the rafters although wood is a pretty good insulator so this is marginal if the insulation is a snug fit between the rafters.
-Paul
I’ve had a couple of recommendations for but it looks like (C) is the one I should be going for. The pic below best describes what I’m trying to prevent (moisture build up).
I like Craig’s idea of painting the underside OSBs with some waterproofing solution.
Do you think I need a vapour barrier between the plyboards and Kingspan insulation panels?
I’ve got no ventilation other than when the door/windows are open.