- Q.Here in Wisconsin, I have
always built my homes with 2x6 studs, R-19 fiberglass
batts, and 1/2-inch OSB sheathing. I am considering
switching to 2x4 studs, R-13 batts, and 1-inch R-7 foam
sheathing, using metal T-braces for racking resistance.
The cost of the two systems appears to be about the
same. I like the fact that the foam sheathing stops
thermal bridging at the studs. My question is: Will the
metal T-braces provide a frame that is rigid
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
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 provide the racking resistance that you need.
In fact, the technical literature by Simpson
Strong-Tie clearly indicates that the metal braces
are for temporary use during construction. They are
not intended for long-term bracing of the framing.
For more information, see "Bracing Foam-Sheathed
Walls," JLC, 4/93.