Section 311. Means of Egress

311.1 to 311.6 {As in IRC}

311.7 Stairways

311.7.1 to 311.7.4 {As in IRC}

311.7.5 Stair treads and risers. {As in IRC}

311.7.5.1 Risers.

The maximum riser height is 8¼ inches (210 mm). The riser must be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs may not exceed the smallest by more than ⅜ inch (9.5 mm). Risers must be vertical or sloped from the underside of the nosing of the tread above at an angle not more than 30 degrees (0.51 rad) from the vertical. Open risers are permitted as long as the opening between treads does not permit the passage of a 4-inch-diameter (102 mm) sphere.

Exception: The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less.

311.7.5.2 Treads.

The minimum tread depth is 9 inches (229 mm). The tread depth must be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. The greatest tread depth within any flight of stairsmay not exceed the smallest by more than ⅜ inch (9.5 mm).

311.7.5.2.1 Winder treads.

Winder treads must have a minimum tread depth of 9 inches (229 mm) measured between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline. Winder treads must have a minimum tread depth of 6 inches (152 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline may not exceed the smallest winder tread by more than ⅜ inch (9.5 mm). Consistently shaped winders at the walkline are allowed within the same flight of stairs as rectangular treads and do not have to be within ⅜ inch (9.5 mm) of the rectangular tread depth.

311.7.5.3 to 311.7.5.4 {As in IRC}

311.7.6 to 311.7.12 {As in IRC}

311.8 Ramps {As in IRC}