What's An Open Riser Staircase?
You can see in the
picture above that there are no wood stair risers on the staircase in
the picture above. This is what most people would refer to as a set of
stairs with open risers. Most building codes give you the impression
that the days of an open riser stairway are numbered.
For most private residences or single-family homes, you're allowed to have open risers, but they will fall into the 4 inch round sphere rule. In other words, a 4 inch round sphere can't pass through the riser areas located throughout the entire stairway.
If you are using a stairway for a building exit, you will need to close the risers. Make sure that you use the correct building materials when closing risers. I worked on a job one time where I needed to use a minimum of 1 1/2 inch thick lumber to close the stair risers. This provided the stairway with a one hour fire protection rating.
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 This information could be incorrect or outdated.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 to some building departments have different interpretations for certain building codes.