I'm considering replacing my Asphalt roof, on my house and detached garage, with a standing seam steel roof. I've seen posts about people experiencing condensation issues after installation of metal roofs and am wondering what the best underlayment and/or method is to prevent this. There are roofing companies recommending the use of "breathable" underlayments like VaproShield SlopeShield or GafElk Deck-Armor that have a high perm rating to allow moisture to escape while preventing it from reaching the sheathing from the top side. Other roofers use a low perm material like Titanium UDL but wouldn't that trap the moisture allowing for rot of the OSB sheathing? My house has a finished attic with only two cross gable vents in the small space above the ceiling triangle and there are roof knee walls so that the ceiling runs at the same slope as the roof. What do you advise to prevent condensation from getting into the house and possibly causing water damage?
Guest User
2010-03-27 00:12:41.000000
Make sure that your envelope and insulation layers line up. I would seal the kneewalls as well as any penetrations in the ceiling. Got to the attic crawlspace and seal all the top plates out to the eaves as well as the floor. That will stop most of the moisture from leaving the space and even having the chance to condense.
Once you have done that, you have solved most of the source of the problem and eliminated the moisture source.
