Assessing the hygrothermal performance of typical lightweight steel-framed wall assemblies in hot-humid climate regions by monitoring and numerical analysis

Lightweight steel-framed (LSF) construction has attracted interest and gained popularity worldwide in recent years; however, due to a lack of knowledge, LSF construction suffers from premature failure related to moisture problems in hot-humid regions. To assess the risk of durability failure in developing LSF assemblies, four typical LSF wall assemblies fabricated with two kinds of construction methods were monitored for 10 months under real environmental conditions in the typical hot-humid city of Guangzhou. Wall assembly can become wet when the weather is wet or the indoor environment is air conditioned. Wall assemblies with a ventilatable cladding system (Wall C) are the least susceptible to wetness, followed by assemblies with a ventilatable cladding system and external extruded polystyrene (XPS) board (Wall A), assemblies with stucco cladding (Wall D) and assemblies with stucco cladding and external XPS board (Wall B). Wall A performs the best in terms of mold growth and corrosion risk, while Wall B and Wall D have the highest risks with regard to mold growth and corrosion, respectively. However, the LSF components could reduce the time of wetness (TOW) on the surface of the external sheeting (insulation) board. The external XPS board could significantly reduce the TOW in the structural cavity, while the stucco cladding system leads to a higher moisture risk. Special attention should be given to the sealing quality of the edges, especially at the bottom, and at the interface between the stucco cladding and external insulation, as these locations have the greatest risk of moisture problems.