The ibc stair codes are slightly different than the ones set by the irc.
Commercial stair tread and riser requirements.
Maximum 12 3 vertical height rise for a flight of stairs.
Risers the vertical element connecting treads that are no less than 6 inches in height and no more than 7 5 inches.
Commercial stair riser height the code specifies that risers should not be more than 7 inches in height and not less than 4 inches when measured vertically between the nosing of the adjacent tread.
Therefore let us recap on the residential stair code requirements.
Stair tread depths shall be 11 inches 279 mm minimum.
The international building code sets the commercial building code for stairs.
The stair tread code requirements are also slightly different with a minimum depth of 11 inches.
The tread depth is the distance from the front edge or nosing a tread projection that overhangs the riser below of one step to the front edge or nose of the next step measured horizontally.
For example the maximum stair riser height is 7 inches and minimum is 4 inches.
1910 25 b 3 stairs have uniform riser heights and tread depths between landings.
Ibc stairs code requirements.
International building code for stair treads and risers 1009 3 stair treads and risers.
Vertical clearance above any stair tread to any overhead obstruction is at least 6 feet 8 inches 203 cm as measured from the leading edge of the tread.
In summary osha compliant fixed stairs must have.
Building codes limit variation to 3 8 10 mm the underside of risers should be sloped or have a 60 angle minimum between nosings and the horizontal surface open risers are not allowed under ada guidelines.
Minimum 6 8 headroom height clearance for stairway.
Spiral stairs must meet the vertical clearance requirements in paragraph d 3 of this section.
The riser height shall be measured vertically between the leading edges of adjacent treads.
Riser and tread dimensions should be continuously uniform for safety.
Maximum 4 1 2 inch handrail projection into stairway width on either side.
The tread depth td is to be 185mm and it should not be more than 30mm shorter than the going g.
All risers and all goings in the same flight of stairs shall be of uniform dimensions within a tolerance of 5 mm.
This distance must be at least 10 inches.
Headroom ibc 1011 3 riser height and tread depth ibc 1011 5 uniform dimensions ibc 1011 5 4 solid risers ibc.
Minimum 36 inch clear width for stairway.
Width and capacity ibc 1011 2 the number of occupants on each floor will determine the required width of the stairs.
Stair riser heights shall be 7 inches 178 mm maximum and 4 inches 102 mm minimum.
Risers goings and treads dimensions.
