Advances in material technology have resulted in innovative solutions for protecting our homes and buildings from the elements, while allowing them to both release vapor buildup and drain bulk water. And with a growing number of products hitting the market to address this need, it’s important to understand how each performs in order to specify the right building wrap for your project.

One method for achieving bulk water drainage is the integration of a rainscreen material onto the building wrap. These products eliminate the cost and time-consuming labor of installing furring strips by creating a gap between the sheathing and the cladding, which facilitates both drainage and continuous airflow. Where wood strapping only vents approximately 85 percent of the wall, building wraps with an integrated rainscreen provide a continuous vented airspace over the entire surface area of the wall, providing greater drainage and more effective drying. And because many rainscreen products use a matrix of plastic material to achieve the gap, they aren’t subject to saturation and decomposition that could compromise wood furring.

Rainscreen products are recommended in areas with wind-driven rain, high amounts of rainfall (40 to 60 inches annually), or high temperatures, and humidity. Coastal areas and hilltop exposures are prime examples of when this technology would be ideal. In these situations, the importance of creating a drainage plane is heightened when using an absorptive cladding material like wood or fiber cement.

Another approach gaining in popularity is the incorporation of unique spacers, or dimples, onto the building wrap itself. These drainable building wraps are able to achieve a 1 mm drainage gap through a pattern of integrated spacers, and can be as much as 100 times more effective than standard building wraps at removing bulk water from the wall. Most can be installed in any direction without affecting performance.

These products are recommended behind wood, fiber cement, vinyl, stone, and stucco cladding, or where budgets don’t allow the use of a full rainscreen system.

At the cutting edge of drainable building wrap technology are products that create a drainage gap through an additional layer of polypropylene fibers. TYPAR® Drainable Wrap, for example, uses this technology to create a 1 mm drainage gap and has been shown to achieve 94.8 percent drainage efficiency per ASTM E2273 without sacrificing any of the durability and ease of installation benefits builders and contractors have come to expect from premium building wraps. In addition, when used as part of the TYPAR® Weather Protection System, it is backed by an industry-leading, lifetime limited system warranty that includes both materials and labor.

Like dimpled wraps, TYPAR Drainable Wrap can also be installed in any direction without affecting performance. And it’s vapor permeable, so moisture will not become trapped in the wall assembly and lead to mold or rot issues.

While we can’t completely stop water from getting into walls, advances in building wrap technology are a welcome way to help ensure potential damage from water intrusion is mitigated. And with a variety of drainable products to choose from, each offering a different approach to bulk water drainage, builders and contractors have many ways to keep walls dry in any climate or condition.

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