Alpine carries out insulation activities for over 800 residential building projects a year. We have an excellent record when it comes to meeting deadlines, passing inspections and providing exceptional service. With 4 full-time estimators and 30 full-time insulators, we are able to meet and accommodate the flexible nature of residential construction projects.
Wall Insulation for New Construction
Typically, this is a wood-frame wall with the potential for insulation in the stud cavity (batts or spray-applied) and on the exterior face of the studs (rigid insulation). See Figure 1. During planning and installation, note the following:
The vapour retarder should be at or near the inside surface of the insulation and would most commonly be 6 mm (0.2 in.) polyethylene sheeting at the inside face of the studs or vapour-retardant paint on the finished drywall.
The air barrier can be provided by the polyethylene vapour retarder, by the interior drywall or by air-barrier sheeting on the exterior face of the studs. In all cases, the air barrier must be carefully detailed to be continuous at all penetrations.
Adding rigid (board-stock) insulation to the outside face of the studs minimizes thermal bridging. Spacing the studs at 610 mm (24 in.) rather than 406 mm (16 in.) where possible will also reduce thermal bridging.
Wall Insulation for Existing Construction
The two most common wall types are wood-frame and solid brick. In a wood-frame wall, insulation (loose fill and some foams) is typically blown into the cavities through holes that have been drilled through the drywall or siding. In solid brick, the largest cavity is usually 25 mm (1 in.) wide, which is not enough for any significant increase in R value. The builder must create a cavity. Usually, a new cavity wall is built inside and insulated as a new wall, or board stock and new siding are applied to the exterior. When planning a cavity wall retrofit, remember the following:
The cost of getting at and repairing the walls is a significant part of the work and cost of the project.
Both air and vapour barriers are required. The interior painted drywall can be both an air and vapour barrier, but details at windows, electrical outlets, floors and other penetrations must be done carefully to reduce air movement through the wall as much as possible. Air movement can lead to mold growth and decay of the walls, as well as loss of insulation efficiency.
An insulation must be selected that will completely fill the cavity and not settle. Some insulations, such as foams, can provide reasonable air barriers themselves.