- Q.Do you need to use
pressure-treated lumber for the bottom plates on
interior partitions over a slab?
A. You won’t need
pressure-treated plates on interior partitions for
crawlspace and basement houses, but you will need
them over slabs. Code requires pressure-treated
lumber wherever framing is in contact with
foundation concrete. Another very good reason to
have pressure-treated lumber plates is to deter
termites. Termites can enter through a crack as
small as 1/64 inch, and the pressure-treated plate
can discourage their entry.