Alternating Tread Device Width

Reduce design time construction costs and installation errors with pre engineered stairs from lapeyre stair.

Alternating tread device width.

These highly adaptable stairs meet relevant building codes and create a safer work environment. The tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads. The projected tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads. 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 stair requires one unit of space per step. 3 means of egress components doors stairs ramps and exit passageways are the most common means of egress components. 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. 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 code also permits fire escape ladder alternating tread devices and slide escapes in certain occupancies. Alternating tread devices and ships ladders alternating tread devices and ships ladders are now permitted as a means of egress for lofts with an area that does not exceed 200 square feet. Alternating tread stairs provide the same space saving benefit but more than twice the usable tread depth as a ships ladder or ship stair. Note that ibc code for i 3 spaces calls for 5 minimum.

On its own this is a great advantage. These stairs allow the user to descend face forward giving a clear view of the floor below. The image on the right illustrates the space efficiency gained by an alternating tread stair. 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 in accordance with section. The alternating tread stair appears in the image s center with green colored treads. The same as the half width step on its left and half as much as the full width stair on its right. More tread depth means a larger stepping surface and greater stability for the user.

The clear width should be at least 18 wide. Precision ladders at series of aluminum alternating tread stairs were designed with tubular siderails to provide maximum structural integrity while keeping. Minimum depth of 4. The tread s leading edge.