Massachusetts Residential Code: Stairs & Guards

Massachusetts builds to the Massachusetts Residential Code, 10th Edition (780 CMR, Chapter 51) — its own edition-numbering scheme, unique among states, now on its 10th cycle. The 10th Edition is based on the 2021 IRC, effective 11 October 2024; a concurrency period allowing the outgoing 9th Edition ended 30 June 2025, so the 10th Edition is now the sole code statewide.

For a house stair, the figures match the IRC baseline — 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. No Massachusetts-specific stair or guard amendment has been confirmed. See the US stair & guard rules for the shared figures, and confirm against the current 10th Edition text for any local amendments.