Understanding The Difference Between Stair Step Depth vs. Tread Depth Measurements in Building Codes
Stair step depth and tread depth are two important terms that are often used interchangeably, but they actually have different meanings.
What is stair step depth?
Stair step depth is the total horizontal distance from the front edge of one step to the front edge of the next. It includes the tread depth and the nosing.
What is tread depth?
Tread depth is the usable or walkable portion of a stair step. It is the horizontal distance from the front edge of the step to the vertical riser that connects it to the next step.
Why is it important to know the difference between stair step depth and tread depth?
Building codes typically specify a minimum tread depth for stairs. This is because tread depth is important for safety. If a tread is too narrow, it can be difficult to walk on and can increase the risk of tripping.
In addition, tread depth is also important for people who use wheelchairs or walkers. A wider tread makes it easier for these people to maneuver on the stairs.
How to measure stair step depth and tread depth
To measure stair step depth, you can use a tape measure. Simply measure the horizontal distance from the front edge of one step to the front edge of the next.
To measure tread depth, you will need to use a framing square. Place the framing square against the front edge of the step and measure the horizontal distance to the riser.
What are the building code requirements for tread depth?
The International Building Code (IBC) specifies that the minimum tread depth for stairs must be 10 inches. However, the tread depth can be as small as 9 inches.
What are the building code requirements for nosing?
The IBC also specifies that the maximum nosing projection for stairs must be 1.25 inches.
Conclusion
It is important to understand the difference between stair step depth and tread depth. Tread depth is the most important measurement for building code compliance. When building or remodeling stairs, it is important to make sure that the tread depth meets all of the building code requirements.
