Capillary break between plywood garage door jamb and stem wall? - GreenBuildingAdvisor
Summary
This article discusses the importance of a capillary break between plywood garage door jambs and concrete stem walls to prevent moisture-related issues in cold climates.
Why It Matters
Understanding the role of capillary breaks in construction is crucial for ensuring the longevity and durability of structures, particularly in cold climates where moisture can lead to rot and structural failure. This discussion provides practical insights for builders and homeowners to enhance building practices.
Key Takeaways
- Direct wood-to-concrete contact can lead to moisture wicking and rot.
- Implementing a capillary break is essential for durability in cold climates.
- Using materials like foam sill-seal or peel-and-stick membranes can mitigate risks.
Capillary break between plywood garage door jamb and stem wall? Izzza | Posted in General Questions on February 21, 2026 08:39pm We’re building a detached garage/hobby outbuilding in Ontario Canada (cold climate) that will be reasonably airtight and insulated aside from an 18 ft overhead door. The 2×6 sill plate sits on a concrete stem wall, protected with Resisto tape. I read that this spot where slab meets framing meets door opening is a common spot for failure in garages. For the door openings, including the garage door, the studs at the jambs are framed flush with the stem wall cutout. Plywood instead of a 2×6 comes down the sides and is fastened to both the stud and the concrete. When I look at this detail, what stands out is that we have no capillary break behind or under this plywood where it touches the concrete. I’m no expert but that doesn’t seem good. Is that wood‑to‑concrete contact risky for moisture wicking or long‑term rot? Should I ask the crew to pull the bottom 6″ of plywood jamb, apply some type of capillary break (tape, peel‑and‑stick, or liquid flashing?), and reattach? Or just leave it… It’s cold here so I’m not sure if liquid flashing would adhere well, but with only 4 small chunks of plywood to deal with, they could just be brought inside and coated if needed. I thought the goal was to prevent any direct wood‑to‑concrete contact, but maybe the risk here is negligible. What’s the best way to handle this detail for durability and longevity? Thanks GBA...
