Do framed interior walls that sit on top of concrete basement floors need pressure treated wood for the base?

Yes, use PT for the base plate.

They sell a moisture barrier that you place between the floor and your joist, this protects it from mildew and moisture decay. In many areas the use of pressure treated lumber in a home is not to code. A fire releases the harmfull chemicals used on this lumber.

My rule of thumb is you never have white wood touching concrete, same for furring out basement walls. Newer PT is arsenic free but you still should not burn scrapes. If the house were to catch fire you'd be leaving the house anyway or be killed by the smoke from about 100 other things in your home that release toxic fumes when burned.

I would suggest checking your local code on this matter.

In my time as a contractor I have seen several codes requiring treated wood on concrete, I have never run into a case in which it is a code violation to use Ac2 lumber. I would agree with ballengerb1, if my house catches on fire the last thing I will worry about is the treated lumber. My personal experience with putting a vapor barrier between the wood and the concrete is it does not work. I have looked through my state and federal code books and don't see anything about it being a violation. HOWEVER... that does not mean the city or county you live in doesn't have some codes of their own.
Mike

I also checked my code book and couldn't find anything, excet for the type of fastener you are supposed to use with PT (Zinc Coated Galvanized). City codes do vary though like Mike said.

Check with building code from your local building office and see what they say.

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Originally Posted by pauto

Do framed interior walls that sit on top of concrete basement floors need pressure treated wood for the base?

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When I remodel basements,I cut 1/2 '' fiber exspansion joints into 4'' squares and place them 16'' on center under the bottom plate of walls, since most of them are non bearing. This keeps the plates dry and in case of an accidental water leak or wet floor may save you from replacing damaged drywall or rotted studs because of wicking.

Bill, your appraoch may work for you just like a barrier mentioned earlier bit it still may not be code. Have you checked code in your state/town? I have not run into any codes that allow white wood to touch concrete.

I agree ballengerb, all the codes I have seen absolutley will not allow un treated wood to come in contact with cement.
Mike