Jeremiah Sommer has been a builder in Ontario for nearly 30 years and has always used either OSB or plywood sheathing. Maybe it’s time for a change.
“Over the last couple years, my company has been moving in the direction of high-performance and Passive [House] building, which has led us down the path of superinsulated walls and all of the good stuff that comes with this method of construction,” Sommer writes in this recent Q&A post.
Sommer recognizes that plenty of builders have skipped conventional sheathing and opted instead for rigid foam over a braced stud wall. But their decisions seem to be mostly about saving money, and not for any reasons related to building science. Now, with newer building materials on the market, does this sheathing-free approach have some performance advantages?
“With the advent of products like Solitex Mento Plus from Pro Clima, which can be used directly over the exterior of a stud wall to create a sheathing-free enclosure and is robust enough to accommodate dense-pack cellulose or fiberglass, is ‘cold sheathing’ still a concern for thick double-stud walls?” he asks.
“To me the idea of installing a skin like this on the exterior with a vented rainscreen and using a smart vapor retarder on the interior of a dense-packed double-stud wall would create a very dry-able wall,” Sommer continues. “I realize that OSB or plywood might be necessary at times as a structural requirement but in situations when let-in wind bracing is suitable a sheathing-free wall seems to make sense. Also, it would be nice and light to stand. “
That’s where this Q&A Spotlight begins.
Consider these disadvantages
Kyle Bentley suggests that Sommer consider some of the consequences of walls without sheathing, including increased fire risk from using foam on the exterior,…