The rafters are 8 inch steel with 8 inch foam creating an R factor of 72. The sidewalls are 6 inch steel studs with foam, for an R factor of R42. The basement is made of foam blocks filled with concrete that create an R50 insulation factor. The interior studs throughout the house and garage are steel studs. Excellent construction creates an exceptionally well-built home that is very fire resistant and a great place to seek shelter in a storm because the house has been strapped at floor and ceiling to be able to handle high winds.