The Passive House Build, Part Two: Air-Sealed Mudsill Assembly
You only have one chance to get this critical detail perfect.
Synopsis: Part Two of the Passive House Build is devoted to “Air-Sealed Mudsill Assembly.” Architect, Steve Baczek writes that the mudsill is one of the most critical components of a successful Passive House. Airtightness is essential to a Passive House. Minor irregularities of the stemwall or shrinkage of the sill plate once the water and preservative treatment dry alone will make a mudsill prone to gaps, which would pose a major problem to the Passive House design. The article gives a detailed process of assembling an airtight, mudsill sandwich comprised of poly, termite shield, EPDM, Pressure-treated 2×6, and, interestingly enough, acoustical sealant.
Watch the videos and read the articles in this series (links below), then head on over to GreenBuildingAdvisor.com to join the conversation with the designer of this house, Architect Steve Baczek.
All articles in this series:
“The Passive House Build, Part One: Designed for Success” (FHB #240)
“The Passive House Build, Part Two: Air-Sealed Mudsill Assembly” (FHB #241)
“The Passive House Build, Part Three: Superinsulated Slab” (FHB #242)
“The Passive House Build, Part Four: Framing for Efficiency” (FHB #244)
“The Passive House Build, Part Five: Installing High-Performance Windows” (FHB #245)
All videos in this series:
The mudsill is one of the most critical components of a successful Passive House. It involves a connection between dissimilar materials, and making such a connection airtight is a challenge. Even the best stem wall will have some imperfections. Also, the mudsill typically will be wet from its preservative treatment and from the lumberyard, and it will shrink as it dries. This means that there likely will be gaps between the wood and the concrete. Traditionally, this part of the building is sealed with a foam gasket. In a Passive House, however, even a…