Modeled and Measured Drainage, Storage, and Drying behind Cladding Systems PDF

Drainage is widely accepted as one of the most effective measures for reducing moisture damage due to rain penetration. As a result, a significant proportion of residential and commercial cladding systems employ drainage as a rain control mechanism. Although drainage is effective, some water is always retained in the drainage space, either as droplets on the surface or absorbed and adsorbed to materials lining the drainage space. Previous ASHRAE-sponsored research has shown that ventilation behind the cladding can remove significant amounts of this retained moisture.

One-dimensional hygrothermal simulation is increasingly accepted as a practical and reliable tool for enclosure wall design and analysis. However, one-dimensional hygrothermal simulation cannot directly model the physics of drainage, storage and ventilation behind claddings. This paper investigates the use of enhancements to one dimensional models that might be used to simulate the hygrothermal performance of drained and ventilated wall systems.

The paper will document the experimental methodology, details, and results and discuss how this information can be applied to modeling drained wall systems. Practical applications and research questions arising from the work are presented.

Presented at Thermal Performance of Exterior Envelopes of Whole Buildings X – December 2007

Units: Dual