Staircase and Wood Tread The central staircase is a key element of the scheme. With the bedrooms and bathroom located on the entrance level, it was crucial to create an intuitive and inviting flow up toward the more social areas. On the upper floor, the central staircase divides and defines an otherwise open plan.  Photo 5 of 7 in A Clever Sunken Roof Fills a London Terrace House with Light