Stringer Stair
Stair type with one or two stringer beams as the support structure.
A stringer stair — also called a saddle stair — has one or two stringer beams on which the treads rest. It differs from housed-stringer stairs in that the treads sit on top of the beam rather than being clamped between lateral stringers. Variants include double-stringer, centre-stringer and offset single-stringer designs.