Alternating Tread Device Ibc

The tread s leading edge.

Alternating tread device ibc. Access to unoccupied roofs egress from mezzanines under 250 square feet with five or less occupants 1 egress from guard towers observation towers and control rooms under 250 square feet 2. Alternating tread devices in accordance with section. Whether you re referencing the seattle building code or the international building code ibc you ll also find exceptions for winder treads ibc 1009 7 3 curved stairways ibc 1009 11 spiral stairways ibc 1009 12 alternating tread devices ibc 1009 13 and ship ladders ibc 1009 14. The international building code and nfpa 101 life safety code use the term alternating tread device 1 2 additional work included in this section some items of work are usually specified in sections other than 05 51 33 23.

Alternating tread stairs provide the same space saving benefit but more than twice the usable tread depth as a ships ladder or ship stair. Ibc compliant applications for alternating tread stairs include. Winder treads shall have a minimum tread depth of 11 inches 279 mm measured at a right angle to the tread s leading edge at a point 12 inches 305 mm from the side where the treads are narrower and a minimum tread depth of 10 inches 254 mm. The projected tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads.

On its own this is a great advantage. More tread depth means a larger stepping surface and greater stability for the user.