The treated material is coated with asphalt to make it water-repellent for use in high moisture areas. Both types of vermiculite are usually installed by hand, a simple process. It doesn't offer as high an R-value as other types of insulation, however. Rigid foam insulation is applied directly to framing as rigid sheets. Several types of foam are available, some with post consumer recycled content made from reclaimed fast-food containers and cups.
Rigid foam is the insulation of choice where space is very limited but a high R-value is needed.
It can be installed on the interior or exterior of a wall, but on the inside it must be covered by a fire-resistant material like wallboard. When the joints between panels are properly sealed, rigid foam insulation can act as both an air and vapor barrier.