Continuous Moisture Protection for the building envelope
Introduction:
In the field of architecture, one area of focus that demands attention is the importance of incorporating a continuous layer of moisture protection within the building envelope. By understanding water vapor migration and its impact on the structure, architects can ensure the longevity and durability of their designs. In this blog post, we will explore the significance of continuous moisture protection and its implications for different climate zones and assembly types.
Understanding Water Vapor Migration:
When designing your exterior enclosure, it is essential to understand the impacts uncontrolled water vapor migration has, as well as how it is transported. Warm air, which can contain higher amount of water vapor than cooler air, seeks equilibrium by moving towards cooler air. When this warm air comes in contact with cold surfaces, it condenses, phase changing water vapor into liquid. Depending on the climate zone and exterior enclosure assembly makeup, this phase change occurs in different locations. When not designed correctly, condensation developing in the wrong location can cause severe structural damage and mold growth. It is essential to design to your climate zone because it determines where the AWRB must be installed within the assembly.
Determining the Location of the AWRB:
The AWRB is typically combined into a single product, but, depending on the design, can be separated into two or three separate membranes. The membranes can be installed in various locations, including the interior side of the insulation, the exterior side of the insulation, or both, depending on the building component and the climate. To understand the recommended location of the AWVB based on different climate zones, you can refer to the Department of Energy's resource guide on continuous air barriers in exterior walls (https://basc.pnnl.gov/resource-guides/continuous-air-barrier-exterior-walls).
Components of a Continuous Moisture Protection Barrier:
We need to design the AWRB to be continuous throughout our building enclosure. This continuous barrier is available in a wide variety of performance characteristics, such as Air Barriers, Vapor Retarders, Roof Underlayment, Roof Vapor Retarders, Ice and Water Barriers, Dampproofing, and below-grade Waterproofing.
The vapor permeance of these barriers must be considered based on climate zone and assembly type, which are classified with a permeance rating and the permeability of materials to water vapor. The term ‘barrier’ implies 0 water vapor transmission. Few products completely stop the transmission of water vapor. Most products should be referred to as vapor retarders, as they reduce the amount and speed of water transmission through the material.
Seek Expert Advice:
To ensure the most effective and appropriate selection of moisture protection products for a specific project, it is always advisable to consult building envelope specialists and product manufacturers. Their expertise will provide valuable insights into the unique requirements and uses based on the project's climate zone and construction type.
Further Resources:
For additional educational content on efficient air barrier applications, the Air Barrier Association of America is an excellent resource to explore (https://www.airbarrier.org/ > Air Barrier Association of America).
Conclusion:
By understanding the importance of continuous moisture protection in the building envelope, architects can enhance the durability and longevity of their designs. Incorporating a comprehensive moisture protection system, considering climate zones and assembly types, and seeking expert advice will contribute to the success of architectural projects and the overall well-being of the built environment.
Written by D.TO: Design TOgether
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