A. Paul Fisette replies: You are correct that wrapping the entire house in foam reduces the problem of thermal bridging at the studs. By elevating the temperature of the stud cavities, the foam also reduces the likelihood of condensation on the interior face of the sheathing.
However, there are three drawbacks to using foam sheathing. First, the foam complicates the exterior trim details at doors and windows. Second, there is the real risk of ants attacking and nesting in the foam. Third, substituting foam sheathing for OSB will seriously compromise a home’s structural rigidity. Metal strap braces alone will not...
to read the full article.