I used all PT 2×4 for framing base plates in my basement, attaching them mostly using a powder actuated nail gun. I did it because I think I read they are more exposed to moisture being directly on concrete, which does have gravel and vapor barrier underneath.
Would it have been okay had I used regular 2×4 instead of PT? Do building codes anywhere require that they be PT?
Best Answer
I've always been told that the sole plate must be pressure treated, when in contact with concrete. I found section 317.1 in the IRC, but it only seems to address "sills and sleepers". It also states that the members only have to be PT, if not separated "from the slab by an impervious moisture barrier.".
Based on the code I've found, I'd say there's no requirement for the sole plate to be PT. Even if it was shoehorned into this section, putting an impervious moisture barrier between the sole plate and the concrete would meet the requirement.
I used untreated wood and installed sill gasket under the walls, when I added framing to my basement. Though it was just a couple dividing walls, so it was never inspected.
I'll continue to search IRC, to see if I can dig anything else up.
NOTE: