insulated sheathing as underlayment
popeye87
| Posted in Energy, Heating & Insulation on
I’m thinking of using 1/2” Celotex Tuff-R with foil face, as a underlayment for vinyl siding. Going to apply it over the existing wood clapboard siding and then install the siding over that. The stud cavities will have blown-in-insulation. Is there a better product? Which way does the foil-face go? Any potential problems with condensation? Seems like I remember reading in T… O.. H…. forum about potential problems with condensation. Thanks for the input!
Replies
foil faces the heat source.
This product belongs on the inside of the studs, not the outside.
Are you saying it shouldn't be used as I'm suggesting?
That's right. It is not a structural sheathing as it provides no diagonal bracing for your wall system. The lack of permeability will trap moisture within the stud bays and cause rot. By using plywood or OSB on the outside and palcing the foil faced foam on the inside you gain strength and insulation without compromising the quality and longevity of the wall.Excellence is its own reward!