Alternating Tread Device Width

These stairs allow the user to descend face forward giving a clear view of the floor below.

Alternating tread device width.

The tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads. Reduce design time construction costs and installation errors with pre engineered stairs from lapeyre stair. Alternating tread stairs provide the same space saving benefit but more than twice the usable tread depth as a ships ladder or ship stair. International building code ships ladder requirements.

On its own this is a great advantage. According to the international building code 2018 ship ladders cannot be used as a means of egress with one exception the exception per ibc 2018 1011. The alternating tread stair appears in the image s center with green colored treads. Alternating tread devices in accordance with section.

3 means of egress components doors stairs ramps and exit passageways are the most common means of egress components. The projected tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads. The tread s leading edge. 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.

Note that ibc code for i 3 spaces calls for 5 minimum. Alternating tread devices shall have a tread depth of not less than 5 inches a projected tread depth of not less than 8 1 2 inches a tread width of not less than 7 inches and a riser height of not more than 9 1 2 inches. The code also permits fire escape ladder alternating tread devices and slide escapes in certain occupancies. Precision ladders at series of aluminum alternating tread stairs were designed with tubular siderails to provide maximum structural integrity while keeping.

The alternating stair requires one unit of space per step. The clear width should be at least 18 wide. The image on the right illustrates the space efficiency gained by an alternating tread stair. 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 same as the half width step on its left and half as much as the full width stair on its right. 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. Precision s aluminum alternating tread stair is an alternative to a traditional ships stair. Minimum depth of 4.