Kyle Diamond

Though I've used Zip System sheathing on several past jobs, I recently began work on a project where we used the insulated panel, Zip System R-Sheathing, from Huber Engineered Woods ( It's basically the same 7/16-inch OSB wall sheathing bonded to either a 1/2-inch (R-3.6) or 1-inch (R-6.6) polyiso foam panel. The project—a new 1,600-square-foot one-story apartment built slab-on-grade—called for R-24 in the walls, which we achieved with R-18 open-cell foam in the walls and R-6 from the R-Sheathing. We planned to install the 4x8-foot panels vertically after the walls were framed and in place, which would reduce the number of seams and keep us from having to install a ton of manufacturer-required horizontal blocking. We also decided to cut out all window openings after the panels were in place.

Framing. The slab wavered up to 1/2 inch in places along the longest wall, so we decided to set the foam sill seal and PT 2x6 mudsills back 1 1/2 inches off the edge of the concrete. This setback would also help protect the exposed edge of the insulation from rodents and insects. Although the R-Sheathing specs allow for 24-inch on-center spacing...

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