Spiral Staircase Systems has designed what it claims is the first example of a helical stair supported entirely by space frame balustrading for a swimming pool at the Throstles Nest site in West Yorkshire.Unlike traditional helical stairs which use solid stringers to support the structure, the Throstles Nest stair has a pair of cross-braced frames running on either side of glass treads, using the top bars to form a double handrail. Stainless steel bars with forked castings at either end are welded to all four tubes. Finally, stainless steel cables pull the frame together. The structure is finished with 12 32mm glass treads leading to a glass landing. Swimmers can also use the back of the stairs as a ladder when climbing out of the pool.