Alternating Tread Device Ibc

Alternating tread devices shall have a minimum projected tread of 5 inches 127 mm a minimum tread depth of 8 5 inches 216 mm a minimum tread width of 7 inches 178 mm and a maximum riser height of 9 5 inches 241 mm.

Alternating tread device ibc.

The tread s leading edge. Clarification r312 1 r312 1 guards the guard requirements only apply to the specific portion of a walking surface that exceeds 30 inches above grade. Alternating tread devices shall have a minimum projected tread of 5 inches 127 mm a minimum tread depth of 8 5 inches 216 mm a minimum tread width of 7 inches 178 mm and a maximum riser height of 9 5 inches 241 mm. 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. On its own this is a great advantage. A device that has a series of steps between 50 and 70 degrees 0 87 and 1 22 rad from horizontal usually attached to a center support rail in an alternating manner so that the user does not have both feet on the same level at the same time. The projected tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads.

If they are to be part of the metal alternating tread stair contractor s work they must be specified here. Alternating tread devices in accordance with section 1009 9. The initial tread of the device shall begin at the same elevation as the platform landing or floor surface. 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.

More tread depth means a larger stepping surface and greater stability for the user. Egress from guard towers observation towers and control rooms under 250 square feet 2. Ibc compliant applications for alternating tread stairs include.