Continuous insulation applied to the exterior of foundation walls reduces expansion and contraction concrete foundation walls would be subject to due to temperature differences between the interior heated space and the exterior air/soil.

Regardless of whether you have chosen a block or poured foundation, you will insulate the perimeter in the same method. The use of exterior foundation insulation reduces the likelihood of frost-heave under footings.

Insulating the exterior surface of the foundation wall provides the advantage of a fully insulated warm wall, which reduces the likelihood of degradation due to freeze thaw and of condensation forming on the inner face of the wall. (In other words moisture won’t drive through your concrete wall and appear on the inside.)

Insulating exterior foundations and perimeters is not just about code, it’s also about protecting the very thing your home is based upon, and increasing the interior comfort. Exterior insulation can be applied at the time of construction or added as a renovation project for increased efficiency and added energy cost savings.

Durofoam Insulating Under a Basement Slab

1. Follow the Building Code

Be sure to follow the building code requirements applicable in your region.

Durofoam Insulating Above a Basement Slab

2. Install Insulation

Ensure that the concrete surface is dry and free of dirt. Starting from a corner, apply PlastiSpan HD insulation boards to the wall from the top of the footings to the top of the basement wall. Use an adhesive compatible with expanded polystyrene (EPS) insulation.

Durofoam Insulating Exterior Foundation Walls

3. Measure & Trim Insulation

Measure and trim PlastiSpan HD insulation with a utility knife or fine tooth hand saw to fit around any openings such as windows.

Durofoam Insulating Under a Basement Slab

4. Drainage at Footing

Place drainage tile covered by coarse gravel at the base of the wall, as per local building code.

Durofoam Insulating Above a Basement Slab

5. Protect Exposed Insulation

PlastiSpan HD insulation must be protected from the top of the basement wall to 12" below grade to prevent damage. Stucco parging is one common protective layer that may be applied. Talk to your building supply professional about other options.

Durofoam Insulating Exterior Foundation Walls

6. Backfill

Backfill the foundation wall to the required grade using backfill material that will permit drainage to the drainage tile at the bottom of the wall. Grade the site so that the top soil is sloped away from the foundation wall.

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