Do I need Tyvek?
I’m retrofitting a 1952 ranch stye house in Connecticut. The wall sheathing is 1×6 tongue and groove. I’m going to put two layers of 1 3/8″ polyiso on the exterior.
Sheathing is now covered with tar paper. I’m thinking of taking of the tar paper (its damaged on a lot of areas) then install polyiso over the sheathing without any Tyvek – Each sheet of polyiso will be caulked around the perimeter. Interior walls ares stripped and will be dense packed with cellulose.
Can I forgo the Tyvek? Seems the aluminum skin on the polyiso is a good air seal. I’ll be installing the insulation and windows and then do blower door test, so i can always have the unemployed college kids go crazy with caulk if I need to. Thanks.