Durability and weatherproofing of building envelope materials




Costello, Vincent K.

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The proper maintenance and long-term durability of the building envelope are two of the most important factors in achieving adequate serviceability of a building. However, products and components are typically tested using fresh and unweathered specimens, leading to a lack of data concerning long-term durability of these components. This thesis investigates various waterproofing material components and assemblies including more elastomeric sealants, clear penetrating water repellent products, and a weather-resistive barrier in the presence of surfactants. These projects are being pursued in an attempt to fill the gap between fresh state material testing and the performance of materials under weathering exposure and a variety of conditions to assess the many factors that contribute to the building envelope’s durability. The data and analysis included in this thesis is a small subset of projects currently in progress at the University of Texas at Austin which also include ongoing investigations into 30+ different materials and components of the building envelope. In this study, more than two dozen elastomeric sealant products from three distinct chemistries were analyzed and their performances compared to assess the influence of product chemistry and starting position (compression vs. extension). It was observed that sealants experiencing early-life compression showed distress sooner than those experiencing early-life tension, but long-term performance is comparable for those products able to withstand initial cycles of compression/extension stresses. Additionally, third-party validation may help a specifier in choosing a product, but this alone may be insufficient in determining products best suited for long-term durable performance. Furthermore, round-robin testing is required to assess the current testing protocols and whether they are truly reflective of performance when installed in real building envelopes.
28 clear penetrating water repellent products from 7 different chemistries were tested for depth of penetration. Silanes tend to penetrate much deeper than siloxanes, silane-siloxane hybrids, and other silicone-based products, with marginal increases in penetration depths with greater active contents. Further long-term testing is required to assess DoP influence on overall durability in preventing water absorption into various substrates. Literature review regarding effects of surfactants in stucco wall assemblies is presented, and bench tests were developed which showed deleterious effects of surfactants on common polyethylene sheet weather-resistive barriers (WRBs). A full-scale testing wall is under construction to investigate mechanisms by which surfactants present in stucco mixtures may affect water-resistive properties of stucco and the underlying WRBs, and a future testing protocol is presented to assess active life of surfactants in hardened stucco to assess potential leaching of the surfactants in hardened stucco.


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