Framing directly against basement concrete – GreenBuildingAdvisor

Replies

1. Expert Member

   BILL WICHERS | Sep 03, 2026 10:04am | #1

   I would put a poly vapor barrier up, and wrap it under the sill plate too. Inspectors might want a treated sill though regardless.

   Bill

1. 

   kickstarter | Sep 03, 2026 10:17am | #2

   Thanks. You’re so helpful, seriously.

   So I can use say a 6mil poly vapor barrier against the concrete and just use regular, non pressure treated 2x4s directly into the concrete? For reference, I have 6 mil visqueen underneath the concrete slab.

1. Expert Member

   BILL WICHERS | Sep 03, 2026 04:26pm | #3

   Against the wall yes, on the floor, inspectors might still want a treated sill, even though it’s not really necassary with a capillary break (poly sheet) wrapped underneath.

   Bill

2. Expert Member

   MALCOLM TAYLOR | Sep 03, 2026 05:09pm | #4

   kickstarter,

   An alternative to using pt wood where it is contact with concrete or masonry, is to use a sill seal between the two.
   
   IRC R-317.1