Previous wind tunnel research indicates that corners and parapets of buildings are subject to concentrated wetting and steep average pressure gradients during wind-driven rain. The initial adaptation of rainscreen design to this information involved the use of different compartment sizes for different parts of the facade, with smaller pressure-equalized rainscreen compartments being placed at edges and larger compartments in the middle. When this strategy was first tested in the wind tunnel, vents were located at the centerlines of the compartments. However, where average pressures change rapidly over the surface, pressure is lower in part of the cavity than at the surface, even in small compartments with centered venting. Since pressures generally decrease toward the edges of the facade for all angles of exposure to the wind, it was proposed to pressurize rainscreen compartments positively by strategic placement of the vents at points of highest average exterior pressure. In addition to eliminating areas where average pressure is higher on the exterior than in the compartment, this approach might alter optimal compartment size and layout.

Research

The report describes methodology and presents the results of a series of wind-tunnel tests on a scale model of a building, where the cavities were partially pressurized by vents located to coincide with high average exterior pressures. The cavities were of various sizes and at various locations at the top and sides of the facade. All locations and sizes were tested over a range of wind angles..

• rainscreen, pressure equalized rainscreen principle : vent location
• wind driven rain

1. An experimental study of pressure gradients and their implications for the design of pressure-moderated rainscreens
2. Simulation of wind-driven rain and wetting patterns on buildings
3. Understanding mold in the property restoration industry  

1. A study of mean pressure gradients, mean cavity pressures, and resulting residual mean pressures across a rainscreen for a representative building
2. An experimental study of pressure gradients and their implications for the design of pressure-moderated rainscreens
3. An exploratory study of the climatic relationships between rain and wind
4. BLWT, CFD and HAM modelling vs. the real world: bridging the gaps with full-scale measurements
5. Simulation of wind-driven rain and wetting patterns on buildings
6. Wind-driven rain study for the Governor's Road Project