The central staircase of this collective housing penetrates the central space of the architecture from the outside to provide maximum floor space. This eliminated the need for an external corridor, significantly increasing usable space. The space below the external staircase has, for example, been used for an internal room. The bold idea to suspend the steel-frame staircase in mid-air was inspired by the need to suppress vibrations and noise from walking on the staircase, as well as to provide ease of waterproofing maintenance. The staircase is hoisted on H-beams and floats in mid-air, making contact neither with the architecture, nor with the ground. Architect Kiko Mozuna's remark at seeing the model that the design was "reminiscent of spiders' threads,” led to the name "The Spider's Thread.” The third and fourth floors are used by the owner of the building as his own house.