In our last article we introduced AeroBarrier. Here’s a quick refresher:
In essence, the system involves blower door pressurization of the house (to +100 pascals), a series of tripods with spray nozzles on them and the introduction of a fine mist of specialized acrylic caulk. From there, much like a balloon with pin holes in it, the pressure drives the sealant to all the small cracks in the building and seals them up. During installation, we monitor the air leakage on our computer and watch the needle drop as the various holes and cracks throughout the house fill with sealant. When we reach our leakage target, we turn off the machine, clear the air with a few fans and open windows and clean up. In most situations, we can take a house from around 7 ACH50 down to below one in under two hours of spraying. The space can be worked in again within about thirty minutes, and once cured, the sealant is a non-toxic, low-VOC substance that is GreenGuard Gold certified for use in schools and hospitals.
In this issue, we present a case study from a recent install in Lake Placid, NY:
We got a call from homeowners in a pickle. During their construction of a kit-built log home (total volume ~44,000 cubic feet), New York adopted a residential building code that requires a blower door test showing air leakage of <3 ACH50 in order to receive a Certificate of Occupancy (C.O.). They needed to be able to move in early this summer, but after their best efforts at caulking likely leak points, the house tested at 5.3 ACH50 (3900 CFM), so it was a no-go on the C.O.
Appliances and fixtures were installed and all finishes were complete except for floors, which had not yet been laid. The owner was quite concerned about the possibility of residue from AeroBarrier on finishes and fixtures, and so we first discussed all possible methods of manually air-sealing. Two features in particular made this a steep challenge: the walls are full round logs with inconsistent gasketing between them, and the ceiling is tongue and groove (T&G) pine with no air barrier applied above it. These two conditions implied thousands of small air leaks that would have required many days’ worth of labor to seal up with color-matching caulking, and even then, there would be no guarantee that the house would reach 3 ACH50.
By using AeroBarrier: 1. We could guarantee the owner that the house would be tight enough to pass code. 2. Because the sealant is essentially self-directed, we could be confident that only the leakage pathways would be sealed, and time and material wouldn’t be wasted sealing up areas that weren’t going to leak in the first place. 3. The owner would be able to confirm scheduling right away with the flooring contractor, and therefore keep everything on track.
Once we received approval to go ahead with AeroBarrier, the house was prepared for the installation: fixtures were bagged or covered, appliances were wrapped, counters and railings were covered with drop cloths. Because AeroBarrier installation goes faster when outside relative humidity goes down, we waited until the following day to let weather conditions dry out. A quick install would help reduce the potential for residue on finished surfaces. The following day we successfully sealed the house from 5.3 to 2.7 ACH50 (1792 CFM) in well under two hours. The owner was amazed at the cleanliness of the finished surfaces after fixture and counter protection was removed. There was virtually zero cleanup. We packed up and headed out, and the project moved forward with a major code obstacle out of the way.
Nate Gusakov is the lead installer for Zone 6 Energy and is based in New Haven, VT.
Zone 6 Energy offers expert air-leakage consulting, AeroBarrier installation, and BPI-certified blower door testing throughout New England and upstate NY.