These days, lots of builders are installing a continuous layer of rigid foam on the exterior side of their wall sheathing. The usual approach is to sheathe the wall with OSB or plywood, and then to install one or more layers of rigid foam outboard of the sheathing.
Some builders are beginning to simplify this process by switching to nailbase panels — rigid foam panels with a layer of OSB or plywood glued to one side. Since nailbase panels provide sheathing and foam insulation in a single panel, they should (in theory) simplify the construction process.
Although nailbase panels were originally developed for use on roofs, an increasing number of nailbase manufacturers are beginning to realize that they can also market their products for use on walls.
At least four manufacturers have developed nailbase-like panels designed specifically for walls:
In addition to these three products, a great many brands of nailbase panels designed for roofs are now being marketed for use on walls.
This article will attempt to address several technical questions surrounding the use of nailbase panels on walls, including these:
Dow Building Products introduced SIS (“structural insulated sheathing”) panels in 2008. Four years later, in July 2012, Dow stopped making the product; however, another company, Ox Building Products of Constantine, Michigan, obtained the licensing rights to SIS and is now manufacturing and distributing the panels under the name Styrofoam SIS.
SIS panels consist of a layer of polyisocyanurate with an 1/8-inch-thick structural facing made out of recycled cardboard. The structural facing is designed to face the interior. SIS is manufactured in two thicknesses: the ½-inch panels are R-3.0, while the 1-inch panels are R-5.5. If builders follow the nailing schedule provided by the manufacturer — a lot of nails are required — SIS panels can be…