Revise and replace the first sentence in R311.7.5.1Risers as follows:
R311.7.5.1Risers. The riser height shall be not more than 8 1/4 inches (210 mm).Revise and replace the first sentence in R311.7.5.2Treads as follows:
R311.7.5.2Treads. The tread depth shall not be less than 9 inches (229mm).Revise and replace section R311.7.5.2.1 Winder treads as follows:
R311.7.5.2.1Winder treads.Winder treads shall have a tread depth of not less than 9 inches (229 mm) measured between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline. Winder treads shall have a tread depth of not less than 3 inches (76 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline shall not exceed the smallest winder tread by more than 3/8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and shall not be required to be within 3/8 inch (9.5 mm) of the rectangular tread depth.780 CMR, ch. 51, ch. 3, R301, 301.1, 311.7
Amended by Mass Register Issue 1532, eff. 10/11/2024.