Bulk water, followed by air leaks that carry large amounts of water vapor, and then water vapor transported through diffusion are the three main modes of water leaks that lead to deterioration within the wall assembly.
Installing and specifying WRABs
Properly specified and installed WRABs can help protect a building envelope from premature decay, save energy, improve comfort, contribute to better air quality, and allow mechanical systems to perform optimally. Building designers should consider obtaining advice from building envelope experts, such as building science specialists or manufacturers’ technical representatives, when selecting materials for the building envelope.
Recent feedback from designers and installers of WRABs indicate the following list of the most requested performance features:
- Maximum compatibility with other products.
- High temperature stability of the installed material.
- Low temperature application of the material.
- Solutions for various UV exposures.
- Clear installation details and designer support.
- Material options to suit the project’s climate region and zone:
○ Permeable or non-permeable.
○ Self-adhered sheets or fluid-applied.
Building codes and standards
What part do building codes and standards play in ensuring the design and installation of the WRABs are considered resilient? Simply put, they do not play a role. Many may argue it is not their responsibility to ensure resiliency—after all, codes and standards have always set reasonable minimum standards. They have done this by systematically evaluating the risks and these risks have always been based on historic experience and data when it comes to weather related events. Benchmarks, such as 50- or 100-year storms, have been considered reasonable and for the most part, accurate in determining guide minimums. However, there are many that believe the trajectory of climate events is on a very steep climb to examples not seen before, so how could codes and standards keep up with such change?
However, all is not lost. There is a growing consensus that the industry needs to do better and there is a larger understanding that although no one has a crystal ball, there is some valuable input being made into predicting the events to come. Based on those models, at least there is understanding as to where things are heading, and this allows for reasonable engineering judgements to be made in preparing for resiliency.3
