Building Science Corporation
November 11, 2011

This retrofit house is located in Lancaster, MA (Cold Climate). It involved building an additional floor and a new roof with a raised heel truss and 18” of blown cellulose insulation at the attic floor. The walls were retrofitted to add two 2” layers of XPS rigid insulation to the exterior of the wall sheathing and closed-cell spray foam insulation in the framing cavities. The windows were replaced with new low-E triple-glazed windows. Closed-cell spray foam insulation was added to the interior of the rim joist and foundation wall. A new basement slab was cast with 2” XPS rigid insulation under the slab. 

Enclosure Design


For complete details on this deep energy retrofit project, go to
National Grid Deep Energy Retrofit Pilot Program—2nd Floor Reframing Comprehensive Retrofit of 19th Century Small Colonial