Vents, ventilation drying, and pressure moderation.

The orientation, size, and nature of vents in screened exterior wall systems are important to wall performance because these characteristics affect venting, ventilation and pressure moderation. The ventilation of screened wall systems has received very little attention in Canadian building research. With funding from CMHC 's External Research Program, the B uilding Enginee ring Group at the Uni versity of Waterloo undertook an experimental and theoretical study of vents and venting in screened walls. The o bjective of this study was to define the problems and potentials, de velop upper and lower bounds of likely performance, and pro vide some theory and complementary expe rimental measurements as a precursor to future more detailed and directed studies. The scope of the study extended to all screened and vented exterior wall systems. Masonry veneer walls were of special interest because of their wide use and the special importance of ventilation to this type of wall.