Aerosol Sealing of Existing Attics and Crawlspaces

This project will evaluate new applications of aerosol sealing, a product used to seal buildings primiarily in new construction, to sealing in existing homes. Previous studies have shown that half of the leakage in new California homes occurs through the attic so addressing leakage at the attic floor has a significant potential to reduce total envelope leakage. A recently completed demonstration as part of a DOE Building America project showed very encouraging results when applying an aerosol sealing technology to an existing attic. Three apartments were sealed by an average of 55% when the aerosol sealing technology was deployed from the attic space. Only the attic floor is sealed allowing the attic to remain ventilated and avoiding any potential issues with condensation that occur in a fully sealed attic. This was compared to two other sealing approaches including traditional manual sealing with foam and an elastomeric sealant which achieved 14% and 26% reductions, respectively. In the past, utilization of aerosol envelope sealing was limited to new construction or major retrofit situations. A key advantage of applying the aerosol from the attic is that there is not noticeable deposition of sealant on surfaces inside the home so surface protection requirements are minimal. In the three applications performed, no prep to interior surfaces was performed, reducing the time and cost for sealing and opening up the market to sealing occupied homes. While the tenants do need to leave the home for a couple of hours during the aerosol injection, the process is much less invasive than other retrofit applications of aerosol sealing and is not harmful to occupants. This project will demonstrate the cost and performance of an attic upgrade that includes upgrading existing insulation combined with aerosol-sealing of the attic-to-home leakage in residential building types typically found in disadvantaged communities. The previous study demonstrating this technique was limited to three apartments and this study is needed to demonstrate in single family homes and evaluate performance across more sites.