Video: Superinsulation Doesn't Work if the Windows Leak

In this installment of Green Building Advisor's "Job Site Visits" series, building science guru Joe Lstiburek explains why insulating a house to the highest standards won't do much good if the home still has significant air leakage. I am always amazed at builders who will upsell to an 18 SEER AC system but then struggle to pass the air barrier blower door testing even down here in climate zone 2 where we only need to get under 5ACH@50PA. I have had exceptional home pass before I find a window open a few inches. Have a home test out at 7ACH is not uncommon until I get to walk the home with the builder at the rough. Framers are the most common culprits, with wallboard installers a close second. I have found that a few extra trips to the home at these phases pay off, but only if the builder leans on the subs to make changes in their practice.