What Is the Load/Weight Calculator?
Calculate structural load requirements for stair construction including live loads, dead loads, and tributary loads per stringer. Understanding load distribution is essential for selecting the right stringer size, fasteners, and connections to ensure your staircase safely supports occupants and materials.
How to Use This Calculator
- Enter the stair width and horizontal run length.
- Specify the design live load (40 psf residential, 100 psf commercial) and dead load.
- Set the number of stringers supporting the stair.
- Review total load, per-stringer load, and code compliance.
Why Accurate Load/Weight Calculations Matter
Stairs must resist both uniformly distributed live loads (40 psf for residential per IRC R301.5) and a 300-pound concentrated load applied to a 4-square-inch area. Under-designed stairs can deflect excessively or fail catastrophically under heavy use or during furniture moving.
Building Code References
Related Tools
Frequently Asked Questions
What is the minimum live load for residential stairs?+
The IRC requires a minimum live load of 40 psf (pounds per square foot) for residential stairs. Commercial stairs per IBC typically require 100 psf.
What is the concentrated load requirement?+
The IRC and IBC require stairs to support a 300-pound concentrated load applied over a 4-square-inch area at any point on the stair.