White Paper- Vapor Barriers (Retarders) and Air Barriers

Air and moisture can get into a home a number of ways. Convective transfer involves moving air, such as a draft around a window or door, electrical boxes, or other wall penetrations. Diffusion refers to moisture moving through a material, similar to a sponge soaking up water. Cavity wall construction typically with fiberglass batt placed into the cavities between studs allows air to pass through and requires an additional, separate vapor barrier, typically polyethylene sheet (Visqueen) or kraft paper facing on the fiberglass batts. Continuous insulation (EPS foam or XPS foam) can also be used as a vapor barrier. Vapor


Asked & Answered: Do ICFs Need a Weather Barrier?


One of the questions we are frequently asked is the need for an additional weather barrier or house wrap in ICF construction. The short answer to the question is no. ICFs are a more effective and higher class vapor and water barrier than any house wrap product. ICFs must only be protected from sunlight and impacts through coverings such as brick, stone, stucco, EIFS, siding, etc. Building wraps such as DuPont™ Tyvek® and other house wrap products are designed to shed bulk water such as heavy, wind-blown rain. They also allow the moisture that occurs in cavity walls to escape. Cavity (stud)