Welcome to Top Tread Stairways! Here's the stair we designed and built for a client who wanted a super-slim, non-intrusive way to access their loft. It's built at the code maximum pitch of 70 degrees and has a 102" overall rise. The build code defines an alternating-tread stair as "A device that has a series of steps between 50 and 70 degrees from level... in an alternating manner so that the user does not have both feet on the same level at the same time." So just think with me; That's how we normally climb stairs isn't it? When we climb a conventional stair, we use half of the step at a time. So the idea of an alternating-tread stair is to save a huge amount of floor space by placing the treads in the position where we would normally place our foot as we climb the staircase. This is a brilliant solution for accessing an upper level when space in tight. Please contact Clyde if you want any type of custom stairs. 916-991-9700