STP922

    Condensation Potential in Wood-Frame Walls

    Published: Jan 1987


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    Abstract

    As a result of steadily rising energy costs, construction practice for light-frame wood structures has changed over the past few years. The use of 152-mm (6-in.)-thick walls and application of high-R-value (thermal resistance value), low-permeance sheathings to 102-mm (4-in.) walls has caused concern for the moisture patterns that may occur in walls. To observe actual moisture patterns and the potential for condensation, test structures were constructed near Madison, Wisconsin, and near Gulfport, Mississippi, for exposure of eight types of insulated wall panels at controlled indoor conditions and typical outdoor weather conditions. Panels were instrumented with moisture sensors and tested without (Phase 1) and with (Phase 2) penetrations (electrical outlets) in the indoor surface.

    Continuous inside vapor retarders effectively prevented cold weather condensation in all the panels. Installation of an electrical outlet changed moisture patterns in both the cold winter climate and the hot, humid summer climate. Although condensation occurred for limited time periods in some panels at both test sites, the moisture content of framing did not rise to critical levels.

    This paper should be useful to building designers, builders, and building code officials.

    Keywords:

    condensation, moisture control, vapor retarder, air leakage, wood-frame walls, foam sheathing, thermal insulation


    Author Information:

    Sherwood, GE
    Engineer, U.S. Forest Products Laboratory, Madison, WI


    Paper ID: STP18494S

    Committee/Subcommittee: C16.16

    DOI: 10.1520/STP18494S


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