Since the stair stringer
is the main structural support for the stairway, you will need to make
sure that you have selected a nice piece of lumber. When I first started
working in construction, all we used was a select grade lumber (the
best), but as prices increased, it wasn't long before I started to see
number 2 and better, otherwise known as construction standard.
Stair Stringer Questions And Answers
Important TipThese are only general specifications that can be applied to lightweight construction projects and it wouldn't be a bad idea to check with a structural engineer, if you are building a heavy-duty stairway. Stairways that are built with the wrong materials will create a safety hazard and serious injuries.
A nice piece of number 2 will work just fine as long as large knots aren't located in the wrong spot, weakening the stringer.
Try to avoid using dried out lumber also, because it will be difficult to cut and nail. Lumber that has been sitting in the sun for too long usually cracks or splits when you nail, cut or even screw into it.
You should also try to avoid using lumber that is too wet, because it will shrink, when it dries, creating problems for the stairway. Often these problems come in the form, of annoying stair squeaks.
Now here's another important tip that you should consider, when ordering your lumber. If you need a 12 foot long piece of lumber, for your stair stringer's, it wouldn't be a bad idea to order 14 footers.
This will give you some room for error, just in case you didn't figure the length of the stair stringers, correctly. It will also provide you with additional room to position your stair stringer pattern, when marking and cutting the rest of your stringers.