Treated Lumber or Plywood
You can use plywood or untreated lumber
on the interior of the house as long as you are at least 5 feet from the
exterior of the house. For this situation plywood is a good choice
because of the ease of cutting a curve. This is hard to do with a
treated piece of 2x lumber.
TIP Use a good construction adhesive under the plywood as a vapor
barrier between the wood and the concrete. As you can see in the picture
above the adhesive is oozing out of the sides.
Glue Between Plywood and
Concrete
A special note please remember to check with
your local building department for their interpretation of the building
code. The stair building codes on this page are what we consider
standard in home construction. We will in no way be liable for your
interpretation of these building codes. Remember the stair building
codes on this page are to give you a basic idea of what will be required
in some cities.