Figure 4-9. Slab-on-Grade with Integral Grade Beam with Exterior Insulation. Click here for an animation.
Figure 4-9 illustrates a slab-on-grade foundation with an integral grade beam. The rigid insulation is placed vertically on the exterior face of the grade beam. This insulation aligns with rigid foam sheathing that covers the framed walls above grade. Additional insulation may be placed horizontally around the foundation perimeter. This can reduce the required depth of the slab in colder climates. Subslab insulation is placed horizontally, and extends down the sloped sides of the grade beam.