Exterior Stairways - 2 Stories or Less
Exterior stairways that
are used for buildings that are two stories or less can be built from
building materials no less than 2 inches nominal thickness.
Remember that nominal thickness applies to the width of construction
standard building materials. Most 2 x 4's aren't 2 inches thick, even
though they're referred to as 2 x 4's. The nominal thickness of a 2 x 4
used in Southern California out of Douglas Fir is 1 1/2 by 3 1/2 inches.
Example: The picture above is a set of exterior stairs built using 2 x
12 stringers and 2 x 12 stair treads. It's not uncommon to find a heavy
duty exterior stairway built using 4 x 12 stringers and 3 x 12 treads.
I've seen exterior stairs built using 2 x 12 stair stringers, along with
plywood treads and risers, so make sure that you check with your local
building department to verify this particular
building code.
Attention: Don't forget to check with
your local building department to verify any building codes on this
website. This information could be incorrect or outdated. Building codes
are updated regularly and some building departments have different
interpretations for certain building codes.
Exterior Stairways - 3 Stories or More