Protecting SIPS from moisture

Vapor barrier - Humid climates, very cold climates, and rooms with higher than normal inside humidity may require additional protection. Rooms containing hot tubs and swimming pools will require additional vapor barrier protection. Consult local building codes for specific vapor barrier requirements.

The builder must also seal-off all openings and fill all voids in the thermal shell of the building. The sealing of panel built homes is important for two reasons.

The first is thermal efficiency, one of the major advantages of SIP construction. By sealing all panel junctures to eliminate unwanted air infiltration, heating, cooling and air exchange can be precisely controlled and energy requirements reduced.

The second has to do with the leakage of humid air into voids, "dead air" spaces, adjacent to panel OSB skins. The presence of humid air and dropping temperatures can result in condensation. Condensation can cause deterioration of panels.

To achieve the maximum long-term value that SIP buildings can provide, the builder must use caulk and foam sealant throughout the building process. Connections and junctures, as well as gaps around doors, windows, and other penetrations must all be thoroughly sealed. Experience has indicated that thermal and vapor sealing at roof ridges and valleys is particularly important and warrants extra attention. It is recommended that roof ridges be filled with a foam sealant to fill the ridge juncture (Please note construction detail) Also, when electrical work is complete, all electrical boxes and wire chases should be sealed. For sealing wood-to-wood connections use construction caulk. For sealing adjacent to EPS a low expansion, aerosol propelled foam is recommended.

A vapor barrier shall be installed at the interior of the ridge juncture of the panels. Aluminum sheet, 6 mil poly or a rubber laminate material can be used for this seal. See Drawing #38-312. There should be no wrinkles or voids that allow vapor drive to enter the ridge juncture.

In addition to the vapor barrier, we recommend the installation of an air-to-air exchanger that is operated by a humidistat.

Copyright: 07/26/2006