Another "Stump the Chump" Solution to a Building Performance Issue

Let's play stump the chump!

Joel Key (pictured right), General Manager of Healthy Home Diagnostics, was quick on the draw for last month’s game – he hit 'send' on the right answer within 20 minutes of newsletter publication! Readers will recall the problem was with a newly built house that didn't pass the building airflow standard. The blower door test revealed that the band joist area between the first and second floors, which by rights should have been inside the house, was directly connected to the outdoors. Joel’s answer: “My thoughts would be that the heated garage is below a vented attic and the plywood sheathing, while going below the insulation, is not extending all the way to the bottom of the band joist and or blocking was not added to each joist bay. Air was being pulled in thru the attic vents (eve, soffit, ridge, etc) through the insulation and gap under the sheathing right into the interstitial space between the floors.”

Thanks also to Macon Parker of Charlotte, NC, who sent us his solution to the problem: “Install a pressure boundary (with plywood or rigid foam) and air seal with spray foam. Additionally we have found that the insulation beneath the floor is often falling down and inadequate and we have dense packed this area with cellulose to act as a partial barrier, as it is often very cost prohibitive to remove drywall, air seal the band joist and install adequate supports for the insulation in the floor above the garage.”

Here is the link: http://www.bpi.org/news_pm_september_2011.aspx#article1