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Water comes in four forms: solid, liquid, vapor and adsorbed. All four forms can cause grief to building owners, designers and contractors. When water causes building problems investigating and… Read More

Adding outdoor air in hot humid climates causes moisture problems right? Sometimes. It depends on the condition of the house before you start to add outdoor air. Contrary to popular belief, most… Read More

The function of a vapor barrier is to retard the migration of water vapor. Where it is located in an assembly and its permeability is a function of climate, the characteristics of the materials that… Read More

Buildings used to be constructed over cellars. Cellars were dank, dark places where coal was stored. People never intended to live in cellars. Now we have things called basements that have pool… Read More

Attics or roofs can be designed and constructed to be either vented or unvented in any hygro-thermal zone (Map 1). The choice of venting or not venting is a design and construction choice not a… Read More

Airtightness testing has long—since the 1980’s—been used to test high-performance housing. The 2012 version of the International Residential Code requires testing of every new home. Recently there… Read More

I have recently written about some aspects of the German Passiv Haus1 housing standard (see BSI-025: The Passive House Standard and the GreenBuildingAdvisor.com) as it applies to cold climates (that… Read More

The control of air flow is important for several reasons: to control moisture damage, reduce energy losses, and to ensure occupant comfort and health. Airflow across the building enclosure is driven… Read More

Driving rain deposition is quantitatively the largest single source of moisture for most walls and roofs leading to building enclosure deterioration. Controlling rain penetration is, therefore, one… Read More

Moisture accumulates when the rate of moisture entry into an assembly exceeds the rate of moisture removal. When moisture accumulation exceeds the ability of the assembly materials to store the… Read More