The Westford Habitat House is a 1,400 square foot, one-and-a-half story single-family house with three bedrooms, two baths and an 816 square foot basement located in Westford, MA (Cold Climate). It features an unvented roof with 2 layers of 2” foil-faced polyisocyanurate rigid insulation with staggered seams above the roof deck and R-40 cellulose insulation between the rafters. The walls consist of 2 layers of 2” foil-faced polyisocyanurate rigid insulation and R-19 cellulose insulation in the stud cavities, with 2” of closed-cell spray foam insulation at the rim joist. The house features double pane, Low-E, argon filled windows. The foundation wall is insulated with 4” foil-faced polyisocyanurate rigid insulation on the interior and the slab is insulated with 2” XPS rigid insulation.