Paint as a Vapor Barrier for Walls of Older Homes.
Abstract
Insulation added to walls of an older home without vapor barriers may cause moisture condensation problems. Such problems appear to be minimal in the Madison, Wis., climate so long as mechanical humidification is not used. However, where a relative humidity of 35 percent or higher is maintained in the older home, troublesome condensation in the walls is likely without remedial measures. And even in homes without peeling paint or other overt moisture problems, buildup of moisture in walls may reduce the effectiveness of insulation. To obtain information on the effectiveness of some commercially available paints as vapor barriers, three types of paint (interior semigloss acrylic latex, exterior acrylic latex, and exterior soya-alkyd resin) were applied to the plaster on selected wall sections. A relative humidity of 35 percent was maintained in the test structure through one winter, and moisture levels were observed in the wall cavity. All of these paints served as adequate vapor barriers (where applied in two coats) to keep moisture in walls at acceptable levels. Labeling commercial paints with perm ratings would help the consumer determine those most suitable for use as vapor barriers. This information should be useful to homeowners and home-improvement contractors. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1978
- Accession Number
- ADA068013
Entities
People
- Gerald E. Sherwood
Organizations
- Forest Products Laboratory