Energy Efficient EPS Insulation for Cold Montana Winters

When our customer in Townsend, Montana designed his new home he wanted it to be super insulated for the cold Montana winters. To do so he used conventional 2×6 framing plus added 11” thick, .9 lb density EPS to the outside of the framing. The 11” of .9 lb EPS added an additional R-Value of 42.35 to the R-22 R-Value of the rockwool insulation between the studs. By installing the EPS insulation on the outside of the studs and sheathing, the insulation is continuous except for windows and doors.

The house is built using a pressure treated wood foundation system and an all wood basement floor over 8” thick 1.8 lb density EPS (R-34.8). There is no concrete. The 2×6 basement walls have 4” thick 1.35 lb EPS (R-16.7) on the exterior and rockwool insulation will be used between the 2×6 basement wall framing also. We hope to provide an update on the energy efficiency of the home after the family has occupied it for a couple of months.