Air Sealing a Home Done Correctly

Hi, I'm Jake with Arrow Building and today we're at our Ridgway Modern project, which is a home our firm is building with Brian Morgan of Brian Morgan Architects here in Columbia, Missouri. Today I wanted to talk to you about this big green box behind me. One of the ways that we can make our home more energy efficient is by air sealing. By creating an envelope that doesn't leak air, we have a much greater ability to control the temperature, humidity, contaminants that might get into our house. So if you go to the store to buy like a cooler, the walls of that cooler are much thinner than the wall of your house. But that cooler does a better job of controlling temperature or by conserving that temperature. Why is this? Well, it's a lack of air leakage. In the past, our homes leaked air almost continuously. The older your house is, the more likely it leaked air on a more regular basis or more dramatically. Current building codes have changed and they now require testing for air leakage. They also have a prescribed allowable amount of air leakage that numbers no more than three air exchanges per hour at 50 pascals of pressure. Meaning that if we pressurize the inside of your house to 50 pascals of pressure, no more than three times an hour is it allowed to exchange all of the air in the inside with new air from the outside. So that's new air three whole times an hour. Can you imagine how much new air in our HVAC system has to condition, filter, dehumidify, and all the contaminants that can get in with that new air just because we're letting that happen three times an hour. So by building a tighter envelope, we can cut operational costs of our HVAC system or our filters. We can also improve the indoor air quality as well, which brings us back to this big green box. So the code requires that you test for air leakage at final inspection. However, if you wait until the final inspection and you're not sure what you've missed or everything that you could have missed is covered up. Our firm tests multiple times throughout the project. We test just the envelope, which is this test. We test after the window install, we test after drywall, and we test at completion. So that's four tests to ensure that our goals are being met. This is why behind me we have a big green box with no windows cut out because we want to test just the barrier by itself, nothing else, and we can't cut the windows out and put the windows in until we've tested that. So our air barrier here is a combination of liquid flashing, pressure sensitive tape, the green zip plywood that you can see, and regular old standard half-inch drywall. So in this home we've framed the entire house without any interior walls. Then we've insulated the ceiling and drywalled the ceiling. It's all mudded and taped, that way it is one monolithic structure on the ceiling in there. It's continuous and it is our air barrier. We bridge from that drywall to the exterior wall using two different tapes. One's the zip tape that you can see behind me, the other is a grace nine-inch vichor tape. Our walls are then air sealed by taping the seams to the zip sheathing, and our joint between the wood frame and our concrete, which is a tricky joint, we use Prosco's fast flash. It's a liquid flashing. It gives us a little bit more flexibility with this irregular joint between the two substrates. So again, the code allows for three air exchanges per hour at 50 pascals. To meet ENERGY STAR you would have to be 2.6 air exchanges per hour or less. And then the most stringent building standard on the planet is Passive House. It allows for six-tenths of an air exchange per hour, so that's 0.6. So following these methods, we should get to one-third of the allowable by code, which means less than one air exchange per hour. It means a more efficient, a more durable, and a more healthy home for our clients. Don't forget to like and subscribe for more videos on building science and best practice methods from us here at Arrow Building. Check us out online at arrowbuilding.com, Instagram, and Facebook. Thanks for watching.