Jul 1, 2017

Initial House Assessments & Sealing Options

Direct of Research Dave Bohac created this resource with Ed VonThruma of Building Knowledge to accompany ongoing aerosol building research. 


Visual assessments of houses under construction for this builder showed an overall high quality of air sealing. This was confirmed by HERS rater reports which showed an average tightness of 1.31 ACH50 which is 56% below the Minnesota code requirement of 3.0 ACH50. While there is some opportunity for the AeroBarrier method to produce tighter houses, the greatest benefit would be a possible reduction in overall sealing costs by eliminating many of the current sealing practices. The house inspections and experience with the AeroBarrier method suggest that over half of the envelope air barrier details could be sealed by the AeroBarrier method.

The AeroBarrier demonstration of the house located in Lakeville Minnesota was very successful. The exterior enclosure of the house was largely complete, but the insulation, drywall, and rim joist spray foam had not been installed. The initial house leakage was approximately 2,200 cfm50 and after 2.5 hours of sealing that was reduced by 84% to 358 cfm50 or 0.64 ACH50. This is 79% below the State of Minnesota code requirement of 3.0 ACH50. It is also 51% less than the average house tightness of 1.3 ACH50 for the four completed HERS rated houses. This very tight construction was achieved without the poly vapor/air barrier in place on the walls and without the spray foam insulation/air sealing of the rim joists. This suggests that the current level of house tightness could be produced without much of the current air sealing when AeroBarrier sealing is applied. The next step is to schedule a meeting with the Building America project team (Ed VonThoma and Dave Bohac) to discuss the initial findings and plan for the AeroBarrier sealing of 5 – 6 houses.