Spray polyurethane foam has been tested and approved for application to both inside and outside of basement walls.
2 lb foam has been tested and approved for application on outside basement walls by the National Research Council of Canada after an exhaustive 2-year study. The only requirement was that when foam is exposed to sunlight, that it be coated with pain.
2 inches of 2 lb foam has been a standard for insulating basement walls for years.
The introduction of one-pound foam provides options as 3 inches of 1 lb insulation has a greater “R” value than 2 inches of 2 lb and at lower cost.
In-floor heating can also benefit from foam insulation. Traditionally, once the ground is prepared, sheets of styrofoam or expanded polystyrene boards are taped or caulked together to provide a base for the heat assembly. The boards can leak at the seams and can also crack as the plumber installs the heating assembly on them. Instead, a layer of 2 lb foam can be sprayed on the ground and is stable, seamless and will support the installation of the heat assembly without cracking or failing.
Source: Green Insulation Technologies