Colorado Building Codes: Local Adoption, No Statewide Residential Code

Colorado has no mandatory statewide residential building code. Individual jurisdictions adopt and amend their own edition of the IRC; the only thing set at state level is a minimum energy code (IECC) floor via the state energy code board.

So there’s no single “Colorado” figure for stair or guard geometry to cite here — it depends on the city or county. As a starting point, the IRC baseline is what most Colorado jurisdictions build from — 7¾ in max riser, 10 in min tread, 6 ft 8 in headroom, 36 in min width, 34–38 in handrails, 36 in guards, the 30 in guard trigger and the 4 in sphere (see the US stair & guard rules) — but mountain and high-altitude jurisdictions in particular may layer snow-load or other amendments, so confirm the adopted edition and any local changes with your building department.