Aerobarrier: the secret weapon to air seal an old home
The key to anything from Energy Star to net zero to Passive House is air sealing -- i.e., ensuring that the air in your home stays in your home and you have control over the interior environment. As is said in building science: "build tight, ventilate right".
From prior blower doors during our energy audit, we knew that we had over 12,000 CFM50 of leakage, even after our encapsulation of the attic.
With the older 1890s-vintage part of the house, there are areas of the house that didn't have sheathing or weather resistant barrier. In order to get the energy savings we wanted, we were going to have to find a way to air seal the house in a much more drastic fashion than one can do with a couple of cans of spray foam.
We also didn't have the budget to pull off all of the exterior. Like most of our renovation, Matt Risinger made me aware of a new product that would significantly change our renovation path.
Aerobarrier works by pressurizing the house with a blower door and then spraying an aerosolized caulking that closes up all of the gaps and cracks in your building envelope.
We got two quotes, and ended up going with SEI Group, a large insulation and air sealing distributor with an Atlanta office.
Their installers had to spend substantial time protecting all of the horizontal, historical surfaces of the home that we were going to preserve, which would otherwise be covered by the caulking.
It took several attempts to get our house to pressurize (SEI had to manually spray foam some areas to get us to a point where the equipment could get the house up to pressure).
At last though, SEI was able to get our house pressurized and start the process. It took over 6 hours, but we were able to get our house down from 15,000 CFM50 to around 300 CFM50, or ~3ACH50.
We’ll do another blower door at the end of drywall for our “final” test out. We’re eager to see the results as we’ll have our spray foam insulation but the penalty of having our doors and windows not covered.
