How Many Stair Stringers Do I Use?

By Greg Vanden Berge

I get asked this question a lot, how many stair stringers do I use when building a set of stairs?

It's common in the construction industry for roof rafters and floor joist to be spaced 16 inches on center and we can also use this basic framing method, to figure out how many stair stringers we actually need.

If you have a stairway that's 48 inches wide and you divide 16 inches  into 48 inches, you will find that you need four stair stringers.

If you're stairway is between 30 and 36 inches you will need three stair stringers.

How many stair stringers you actually need will also be determined by the thickness of your stair treads. If you're going to use a 4 x 12 stair tread, there's a good chance you would only need one stair stringer at each end of the stairs, if you're stairway was less than 40 inches wide.

If you're going to use 2 x 12 stair treads, you could space your stair stringers 24 inches on center. The thickness of the stair tread will affect the amount of stair stringers you actually need, but you can't go wrong with the original 16 inch on center measurement, unless you're going to be using stair treads that are less than 3/4 of an inch in thickness.

This article is only meant to provide someone with a general idea but cannot be used in every situation effectively.

Stairs  Stair Articles