Laboratory measurement and boundary conditions for the water vapour resistivity properties of typical Australian impermeable and smart pliable membranes
Olaoye, TS and Dewsbury, M and Kunzel, H, Laboratory measurement and boundary conditions for the water vapour resistivity properties of typical Australian impermeable and smart pliable membranes, Buildings, 11, (11) Article 509. ISSN 2075-5309 (2021) [Refereed Article]
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The duo of better insulated and more air-tight envelopes without appropriate consideration
of water vapour diffusion and envelope moisture management has often demonstrated an increased
potential of moisture accumulation, interstitial condensation, and mould growth within the building
envelope. To inform a resilient, energy efficient, and healthy building design, long-term transient
hygrothermal modelling are required. Since 2008, concern has been raised to the Australian building
regulators regarding the need to establish the vapour diffusion properties of construction
materials, in order to develop a hygrothermal regulatory framework. This paper discusses the
results from laboratory testing of the vapour diffusion properties of two common reflective pliable
membranes, and one smart pliable membrane. The two reflective pliable membranes are often used
within the exterior walls of Australian buildings. The smart pliable membrane is a relatively new,
internationally available product. The three membranes were tested as per ISO 12,572 at
23 ◦C and 50% RH. To establish if the vapour resistivity properties were constant, under
different relative humidity conditions, the membranes were further tested at 23 ◦C and relative
humidity values of 35%, 65%, and 80%. The results of the three pliable membranes show that the
vapour resistivity properties varied in a non-linear (dynamic) manner subject to relative humidity.
In conclusion, this research demonstrates that regardless of the class, each of the tested membrane
types behaved differently
under varying relative humidity and pressure gradients within the testing laboratory.