Water Resistant Barrier

A sheet, spray- or trowel-applied membrane or material layer that prevents the passage of liquid water even after long or continuous exposure to moisture.

Weep Holes

An opening placed in a wall or window assembly to permit the escape of liquid water from within the assembly or component. Designed correctly weep holes may also act as vents.

Wet bulb temperature

Temperature of wet wick slung through the air so that it cools by evaporation; surrogate for enthalpy; fortuitous phenomenon, has no scientific basis.


The phenomenon of air movement driven by wind pressures wind passing through the thermal insulation within enclosures, causing significant loss of heat flow control and potentially causing condensation. Typically occurs are exposed building edges, such as at the outside corners and roof eaves because of the large pressure gradients at these locations. This can be thought of as the “wind blowing through the insulating sweater” effect.


abbr. Wärme Und Feuchte Instationär. A modeling program for simulating one-dimensional dynamic heat and moisture transfer through building enclosure.