This is the third article in our series highlighting our experiences installing AeroBarrier around New England– here’s a quick refresher on the technology:
AeroBarrier® is a patented, cutting-edge envelope sealing system that simultaneously measures and seals building envelope air leaks. Here at Zone 6 Energy, we like to call AeroBarrier ‘Fix-A-Flat for a house’. In essence, the system involves pressurizing the house (to +100 pascals) with a blower door, setting up a series of tripods with spray nozzles on them (just like mini snowmaking guns), 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 target for leakage, we turn off the machine, clear the air with a few fans, open windows and clean up. 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.
Here, we share our experiences air-sealing a brick Colonial near Saratoga Springs, NY that was built in 1738!
The project involved partial renovation of the interior of the house as well as two new additions married to the old brick structure. The owner did not have a specific leakage target in mind but wanted to make use of AeroBarrier’s ability to significantly improve the building envelope performance in a single application without lengthy diagnosis or manual air-sealing work.
Our pre-test showed the building to be quite leaky, measuring 11.9 air changes per hour at 50 pascals (11.9 ACH50). By way of comparison, many northern states have adopted a building code that requires all new construction to measure three ACH50 or less, and, to qualify as a Passive House, a building must measure 0.6 ACH50! After discussing the desire to dramatically reduce air leakage while still leaving enough natural infiltration to avoid the need for installing ducted mechanical ventilation, we established a goal of under five ACH50.
Next we prepared the house for AeroBarrier, protecting any finished horizontal surfaces and ensuring that no gaps larger than ½” remained in the envelope. AeroBarrier is essentially self-guided (with the sealant only being driven to the places in the building envelope that are leaking), so the confusing prospect of trying to diagnose leakage pathways through new and old interstitial spaces was unnecessary.
In the following two pictures, you can see how even properly-installed spray foam can fail to address many air-leakage pathways. In the picture on the left, a strip of sill-seal struggles to fill the void between new addition framing and old stone. On the right, daylight shows between framing members under a window. AeroBarrier addressed both of these leaks automatically. In under 2 ½ hours of install time, we were able to bring the house to 4.9 ACH50. This represents a 59% reduction in air-leakage, and renovation work commenced the following day!
Nate Gusakov is a Lead Installer for Zone 6 Energy. Zone 6 Energy is a home-grown Vermont company specializing in air leakage diagnostics and consulting. They offer commercial and residential blower-door testing, home energy audits, and AeroBarrier installation throughout New England and upstate New York.