Alternating Tread Device
When it comes to maximizing space, who can argue with the practicality of an alternate tread staircase?
The tread depth and riser height are exactly the same as on a standard set of stairs yet because half of each tread is omitted the run is thus reduced by half as well. The angle of incline could be anywhere from 50 to about 68 degrees which falls in line with a pull-down stair or ladder, and that this nifty device pictured has successfully replaced. Here, the alternate tread design serves to access seasonal space in a lightly used attic room and is finished in a handsome stately red oak.
The owners of the home comment on its safety and efficiency, its fine furniture-like finish, and the ability to descend the stair facing forward-just like on an upscale boat.
Check first with your local building code. Many do not cover this design, though there is a compliance chapter in the Life-Safety Code for use as an access to unoccupied roof spaces.