Validating moisture-safe energy efficient CLT assemblies in hot and humid climates using experimental testing

Abstract

Climate specific cross-laminated timber (CLT) construction detailing to manage moisture risks in subtropical and tropical regions of Australia is validated through experimental testing, statistical analysis, and computational hygrothermal modelling. Three projects in Australia are monitored: a CLT micro-unit built in a subtropical climate, a small CLT structure assembled inside a controlled double climatic chamber simulating a tropical environment, and an existing residential building located in a tropical climate. Several parameters are altered in the experiment design to understand the most reliable assemblies for CLT buildings in hot and humid climates that can sufficiently control the moisture risks. The findings suggest that the hygrothermal modelling guidance from ASHRAE 160 pertaining to construction unprotected from stormwater accurately represents CLT assemblies in hot and humid climates. The importance of adhering weather resistant membranes (WRB) to both the external face and edge grains of the CLT panels is revealed. In tropical climates, the positioning of internal insulation and WRB with increased vapour resistance are also shown to be beneficial, while ventilated cavities and drainage layers behind the cladding is critical for rain protection.