Tread Depth Explained: How Deep Should a Stair Step Be?

The 2021 IRC sets minimum residential stair tread depth at 10 in / 254 mm (R311.7.5.2), measured horizontally between the leading edges of adjacent treads — build shallower than that and the stair fails inspection before comfort is even part of the conversation. In practice, most builders target 10.5–11 in / 267–279 mm, because the…