Aerosol Sealing of Existing Residences

Dave Bohac, P.E.

Project Update

Recruitment for the remainder of the project was put on hold due to the COVID-19 pandemic and subsequent lockdown, but the project team is now starting to recruit again. One house participating in the project has already been sealed. This house showed significant leakage, and aerosol sealing managed to bring that leakage below the current code requirement for new homes. Read the full update.

Why This Research Is Needed

Existing houses are notoriously leaky with unintended airflow from outdoors that results in additional space heating and cooling equipment loads. Manual methods for sealing air leaks within a building, even when diligently applied, can fall short of the ultimate tightness goal due to unrecognized leakage pathways. Although voluntary standards (i.e., not legally mandated) for envelope tightness have existed for decades, they have only become codified recently, and they only apply to new construction, not existing residences. 

The aerosol sealing process involves pressurizing the building while applying an aerosol sealant “fog” to the building interior (see below). As air escapes the building through leaks in the envelope, the sealant particles are carried to the leaks where they make contact and stick, sealing the leaks. A standard blower door fan is used to pressurize the house, and also provides real-time feedback and a permanent record of the sealing that occurred. The technology is, therefore, capable of simultaneously measuring, locating, and sealing leaks in a house.


Project Process and Expected Outcomes

The findings of this project will be used to drive market transformation and develop a best practice guide for cost effective aerosol envelope sealing of unoccupied, existing homes and multifamily units.

Researchers will identify the best methods for aerosol envelope sealing of unoccupied, existing residences to improve tightness by 75 percent. Options will be evaluated for improved sealant formulations that are better suited to existing buildings, surface protection methods that allow successful sealing while limiting clean-up costs, inspection procedures to identify larger gap leaks the aerosol will not seal, alternative spray configurations (e.g. introducing spray in the attic with house depressurization), and possible approaches for sealing exterior duct leaks.

This project is funded in part by the U.S. Department of Energy, Building America program. Read the news release. 

Project Info

2019–2021 (24 months)
Develop a best practice guide for cost-effective aerosol envelope sealing of unoccupied, existing residences, to help increase envelope tightness by 75 percent.


  • Year 1: Field test new sealant on a total of eight homes in at least two states.

  • Year 2: Perform aerosol sealing on an additional 20 residences and develop a protocol for cost-effective air sealing.

Non-Energy Benefits

  • Improved occupant comfort by reduced drafts.

  • Improved indoor air quality by reducing the intrusion of outdoor air contaminants into the house (ventilation from mechanical systems can filter or treat outside air before it enters the house).

  • Limit air transport through walls, avoiding moisture damage.

Project Team
UC Davis — Western Cooling Efficiency Center (WCEC)
Aeroseal, LLC
Dave Bohac, P.E., CEE 
Curtis Harrington, WCEC

U.S. Department of Energy