If you’re building a tiny home with a loft and want to pull a permit, your stairs need to meet Appendix AQ of the International Residential Code. This is the section added specifically for tiny homes under 400 square feet. It relaxes the standard stair requirements — regular code would eat up too much floor space in a small build — but you still have to follow specific formulas for rise and run.

This post walks through how the math works and includes a calculator that handles all of it for you.