Weatherstripping a home may not be the most captivating of topics, but I’ve found two new methods to air-seal a home this year that really stuck with me, so to speak. One is pretty basic, using a seemingly mundane material—tape. Not just any tape, but a super sticky tape. The Swedish tape manufacturer SIGA has a line of such tapes designed to stick to and seal just about any seam in a house, whether it’s between two sheets of drywall, between drywall and wood, or around penetrations in the building envelope, including masonry. It has vapor- and non-vapor-permeable options, as well as options for hot surfaces such as those around exhaust flues.
These tapes have been used in Europe for several years to achieve extremely low air-infiltration rates (enough to meet Passivhaus requirements of less than 0.6 air changes per hour at 50 Pascals air pressure (ACH@50 Pa) and are just beginning to make inroads in the United States. The material cost is high at $30 to $120 per roll, but SIGA told me that a two-person crew could tape-seal a typical single-family home in a day. I don’t know if the labor savings compared to that required by traditional sealing methods would result in a more cost-effective solution, but the technology appears to be a way to produce an extremely well air-sealed home. Because these tapes are new to the North American market, we’d love to hear about any real-world experience with them. Tell us your stories in the comments section!
The other air-sealing method is more high tech and is similar to the established Aeroseal duct-sealing process, which we first wrote about nearly two decades ago. This process uses a gooey aerosol-based sealant that’s blown through ductwork. As it passes through holes, it sticks to their sides and gradually closes them off. The same process is now being tried by the Western Cooling Efficiency Center (WCEC) at UC Davis for sealing building envelopes. In this new application, standard blower-door equipment typically used to pressurize and check for air leaks in a building can be used to create the pressure required to drive the sealant particles to the leaks in a building. Just like with ducts, as air finds its way to the leakage points in the envelope, it brings along the sealant, which sticks to the sides and gradually closes off the holes.
In one experiment in a new home under construction, Aeroseal reduced the ACH@50 Pa from 10 down to 5 after a couple of hours of application—without sticking to the walls! The results likely would have been even better if the project wasn’t cut short due to time constraints. In another experiment, an existing home was sealed after it was sold and before the new owners moved in, taking the ACH@50 Pa from 1.5 down to 0.4. Given the standardized application approach of this aerosol method and its ability to seal small air leaks, it could produce more-consistent results, reduce the opportunity for sealant-installation errors, and produce tighter envelope seals than traditional methods. This new application of the existing aerosol process is just in the research stage, so we’ll have to wait to see what its full potential is. Additional field experiments are being planned and more information can be found on the WCEC site: Aerosol Building Envelope Sealing Demonstration.