Building Science Corporation
September 6, 2011

This retrofit house is located in Belmont, MA (Cold Climate). It involved adding three layers of 2” foil-faced polyisocyanurate rigid insulation above the roof deck and netted cellulose insulation in the rafter cavities. The walls were retrofitted to add two 2” layers of foil-faced polyisocyanurate rigid insulation to the exterior of the existing wall sheathing and cellulose insulation in the framing cavities. The windows were replaced with triple-glazed windows. Closed-cell spray foam insulation was added to the interior of the mud sill and foundation wall along with the addition of metal stud walls with rockwool insulation. A new sub-slab perimeter drain was added by replacing a portion of the existing slab and the slab was left uninsulated.

Enclosure Design


For complete details on this deep energy retrofit project, go to
National Grid Deep Energy Retrofit Pilot Program–Two-Family Belmont Residence