The Mallett House Retrofit is a deep energy retrofit of 57 Depot Street; one of several worker cottages built in 1886 for employees of the local shoe factory. In 2010, BSC was retained by Freeport Community Services to propose retrofit enclosure assemblies. These assemblies included 2 layers of 2” foil-faced polyisocyanurate insulating sheathing on the roof and walls, cellulose in the rafter and stud bays, a fully-adhered air barrier membrane installed over existing board sheathing, spray foam and cellulose in the basement wall assembly, a new insulated basement slab, and new high R-value windows. The project team was able to implement all of the proposed assemblies with some modifications resulting from negotiations with the historical society. These included installing 2” of insulating sheathing on the walls and insulating the front façade from the interior in order to preserve the exterior detail. The high performance enclosure and dedication from the project team were what led this deep energy retrofit to achieve a final airtightness test result of 0.68 ACH50. For additional information about the Mallett House Retrofit project, click here.