Moisture Control in New Residential Buildings

Key Points discussed in this article:

Moisture damage in building assemblies is the result of moisture movement caused by rain entry from above or below grade, air transport and vapour diffusion, or a combination of these mechanisms.

Strategies to prevent wetting from the exterior of the building are similar in all climates.

Strategies to control wetness caused by air transport and vapor diffusion are dependent on climate, the time of the year, the buildings interior environment and mechanical system.

Capillary breaks, drainage planes, and the use of semi-permeable materials are used to minimize the risk of moisture movement from rain and ground water.

Air Barriers and Air Retarders are designed and constructed to control air transport, where as Vapor Barriers and Vapor Retarders are used to control vapor diffusion.

The relative humidity adjacent to all building surfaces must be maintained below 70% to prevent surface mold and other biological growth.

Moisture control practices in Cold Climates, Hot-Humid Climates and Mixed Climates are broken down into:

  • Key Concerns And Control Strategies
  • Condensation Within Building Assemblies
  • High Interior Humidity Resulting In Mold And Surface Condensation
  • Mechanical Concerns
  • Combustion Appliances

A comparison of climate appropriate Roof, Wall and Foundation designs.

Moisture Control for New Residential Buildings, Building Science Digest