The roof has conventional trusses, (5/12 pitch) and the insulation will be cellulose over the ceiling drywall.
The ventilation will be through soffit vents and out ridge vents.
The roof sheathing will be 5/8" plywood and the metal panels will be the exposed fastener type.
The question is: What is the ideal way to install the metal roofing panels, or rather, what should go between the metal panels and the sheathing ?
I was thinking of putting felt over the sheathing and the metal panels directly on top of the felt, screwed to the sheathing.
But should there be something else or something additional between the sheathing and the metal panels ?
Such as an air gap or a layer of foam insulation to prevent condensation on the underside of the panels ?
Or will the sheathing plus the layer of felt be enough 'insulation' to prevent condensation under the metal panels ?
( I built a metal carport once and when the humidity was right, it 'rained' from condensation on the underside. Of course it had 'no' insulation, and being a carport, the condensation didn't matter much.)
Thanks,
Arky
There should definitely be a moisture barrier of some type. Felt is ok. Most metal roof manufcturers will go along with the metal on the sheeting vs perlins. The condensation which should be very little will weap down to the edge at the bottom. This should be minimum since you are insulating the space below. Others may have a different opinion. A certified installer help me put mine on and said there shouldn't be any problem. The only difference is I used Titaninum Felt rather than builders felt.
Here is an additional link that should answer most of your questions. If you read in the installation series it refers to felt paper and the more recent materials such as Titaninum Felt.
http://www.extremehowto.com/xh/article.asp?article_id=60253
What he said.