- Q. How is wiring accommodated in a house built with stress-skin panels? Is it possible to rout a channel in the panel to retrofit a wire?
A.Steve Andrews responds: Most manufactured panels have built-in electrical channels. These channels are typically 1-inch holes running through the center of the panel section, so they are well out of the way of drywall screws. They usually run horizontally 12 to 16 inches off the floor, or at about 44 inches (countertop height).
In addition to the horizontal runs, the panels have vertical channels. In some cases, these are placed in the center of the panels, so you have a rise for the wiring every 48 inches. In other cases, there is a notch behind the 2x4 spline that joins each panel. In either case, you have to drill a 1-inch hole through the plates as you set the panels. You then cut in switch and outlet boxes and fish your wires. Obviously, this process is more time-consuming than running wire in a conventionally framed home. And since fishing wire horizontally is so time-consuming and difficult (especially around corners), it’s best to run more of the wiring in the floor cavity than you might ordinarily. In slab-on-grade homes, you have to run some wires as you set the panels, which lengthens the process even more.
For that occasional added light switch or outlet, you can rout a channel out, lay the wire in, and then foam it in place. Unless the panel has integral studs, never rout more than about 8 inches horizontally, or you’ll destroy the strength of the panels’ skin. Vertical runs should stop at least 14 inches from the top and bottom of the panel, which means you have to have a pretty long bit to finish the hole and drill through the plates.
When foaming the wires in, I typically bring the foam flush to the surface of the panel’s skin. Later, this foamed-in channel will be covered by drywall. In the case of a retrofit, when the drywall is already up, leave the foam recessed, so you have room for mud to patch over the channel. To avoid a hassle with the code inspector, you have to rout at least a 1 1/4-inch-deep channel (or, when drywall is up, at least 1 3/4-inch-deep), so drywall screws will not pierce the wire.
The bottom line with all these recommendations is check with the manufacturer. It may have a choice of options and specific guidelines for using its product.
Steve Andrews is the author of Foam Panels and Building Systems (published by Cutter Information Corp., Arlington, Mass.).