Excerpted from a full page article on installing exterior foam insulation at: http://www.greenbuildingadvisor.com/s...

A THICK SKIN THAT KEEPS A HOME WARM AND DRY
Foam sheathing can be your insulation, air barrier, and drainage plane all rolled into one.

Sheathing with foam-board insulation is a great way to get more R-value with a conventionally framed house. It can work just as well in remodeling projects as in new construction. Applying rigid foam takes some getting used to, but the basic tasks are not that much different from installing typical plywood or OSB sheathing—and the lightweight foam is easier on your back...

For more information read the full article at: http://www.greenbuildingadvisor.com/s...