The Best Weather Barriers For New Home Construction
Water will always find its way inside a building, even with new technology and modern materials. A hundred years ago this wasn’t a problem because older buildings had more air leakage which allowed water in the wall cavity to evaporate before it damaged the structure. However, while air moving through the wall allowed water to dry, it was terrible for occupant comfort and energy efficiency. As houses become more airtight and energy-efficient, there is no way for the water to escape once it is inside the home, and water that sits on wood for long periods of time eventually damages the wood. The more energy-efficient and airtight a home, the more susceptible it is to mold and wood rot.
However, building science allows for the solution to this problem. “Proper installation of a housewrap—also known as a water-resistive barrier (WRB)—preferably with a rainscreen behind the wall cladding, enables us to build resilient homes that will last for generations,” Matt Risinger says in his article entitled Weather Barrier Update: Good, Better, Best. In this article, Risinger shares his experience as a builder about the best systems available for keeping water away from sheathing and framing.
There are certain design considerations that when taken into account will decrease the likelihood of water entering and damaging the home, explains Risinger. The first design to consider is roof overhangs, which keep rainwater from hitting the walls of the home. The second consideration is roof pitch: for example, flat roofs are more likely to leak than steeper roofs. The third is wall height. A three-story home has more places for water to enter it than a one story home. Location, however, plays a big part as well. A building in Seattle will see significantly more rain than one in Arizona.
The design and climate of the property determines the degree of protection a home or business needs. According to Matt Resigner, a small building in a relatively dry climate only needs good protection. For example, a one story home with overhangs in an area with less than 30 inches of rain annually needs good protection. As the size of the building increases and the annual amount of rainfall increases, a building needs better protection. For example, a two-story home in an area with more than 30 inches of rain annually would need better protection. The best protection is needed in coastal areas that typically see more than 40 inches of rain annually, or in homes with no overhangs. But what are good, better, and best weather barriers?
Good protection allows water to escape the wall. This kind of protection is generally textured and creates a small gap between the back of the cladding and the sheathing. This gap allows water trapped behind the cladding to drain to the ground. This kind of housewrap comes in a variety of textures and patterns. Better protection usually involves installing a rainscreen under the wall cladding. An engineered rainscreen like DELTAⓇ-DRY provides drainage and ventilation, as well as a complete capillary break behind the cladding.
The best protection involves fluid-applied membranes or peel-and-stick membranes used in conjunction with a rainscreen. One such product that falls under the best protection category is DELTA®-VENT SA, which is a self-adhesive, water and air resistant barrier. DELTA®-VENT SA has three layers. The two outer layers are composed of a high strength spun-bonded polypropylene fabric, and they are thermally bonded to the middle layer, which is watertight and polymeric. DELTA®-VENT SA also has a full surface coating of a high tack adhesive for bonding to common building materials. DELTA®-VENT SA makes an effective weather barrier for new home construction by being vapor permeable. This allows moisture caught within the building enclosure to escape through the membrane via diffusion.
No building is completely water-resistant. However, with the right design considerations and proper protection, mold and wood rot is preventable. Try DELTA®-VENT SA for your building. It is one of the best weather barrier systems available.
Dörken delivers innovative, high-performance air and moisture barriers for commercial and residential construction sold under the DELTA® brand name. A North American manufacturer based out of Beamsville, Ontario, Dörken Products, Inc. is a subsidiary of Ewald Dörken AG, a leading European developer and manufacturer of waterproofing and drainage products sold worldwide. Dörken is known for delivering premium products while providing educational programs and full technical support. For more information, call 1-888-4DELTA4 (433-5824) or visit www.dorken.com.