continued

The insulation can be cut at a 45-degree bevel (Figure 5). This solution, while it does not provide full vertical face insulation, is allowed in Section 502.2.1.4 of the 2000 International Energy Conservation Code (IECC).

Rigid insulation can be used as the bond break material between the slab and footing (Figure 6). This solution requires that you have a notch in the foundation wall.

A 2 x 8 pressure-treated mud sill can be placed on the stem wall to cover the top edge of the insulation (Figure 7). A tack strip can then be attached to the mud sill.

Is there any way to eliminate perimeter slab insulation completely?

Perimeter slab insulation can be "traded-off" using a software tool like MECcheck or COMcheck, from the U.S. Department of Energy.

Additional insulation can be added in another part of the structure to compensate for the missing insulation in the slab. The code permits this trade-off, but when carpet is placed on a cold slab, the higher humidity levels that result can attract dust mites and mold.

How do I protect perimeter slab insulation from moisture and termites?

One option is to install the insulation inside the foundation wall and provide a protective membrane (termite shield) between the sill plate and foundation (Figure 8).

What are the requirements for slab insulation in the IECC 2000?

The table below summarizes the prescriptive insulation requirements for residences in which Window area is 15 percent of gross exterior wall area.

Heating Degree Days	R-Value	Width in feet (meters)
0-2499	0
2500-4499	R4-R5	2 (0.6)
4500-6999	R6-R9	4 (1.2)
7000-12999	R13-R18	4 (1.2)

This summary was taken from Table 502.2.4(3), p.81, IECC 2000, from Building Officials and Code Administrators International, Inc. (BOCA).

For more information on this topic see the Energy Efficient Building Association's Builder's Guide from the Building Science Corporation or the Builder's Foundation Handbook Publication number ORNL/CON-295, Oak Ridge National Laboratory.

This article first appeared in Setting the Standard, the newsletter of Pacific Northwest National Laboratory.

Or, the insulation can be applied vertically inside the foundation wall. Image: Pacific Northwest National Laboratory The insulation can also be placed horizontally under the slab. Image: Pacific Northwest National Laboratory A method to avoid bringing the insulation to the top of the slab edge. Image: Pacific Northwest National Laboratory Rigid insulation can be installed in a notch in the foundation wall. Image: Pacific Northwest National Laboratory A 2 x 8 pressure-treated mud sill on the stem wall can serve as the carpet tack strip. Image: Pacific Northwest National Laboratory A termite shield between the sill plate and foundation can also protect against moisture. Image: Pacific Northwest National Laboratory   Click on thumbnail images to view full-size pictures.