A mono stringer, usually. One central spine takes up less width than two stringers set under the treads, which matters in the narrower stairwells common in Tacoma's older houses. A cantilever also leaves the open side clear, but depends entirely on what the supporting wall can carry.

Considerably better than a conventional stair. Open risers and minimal visible structure remove most of the mass from the sightline, and pairing the stair with a frameless glass balustrade takes it further. On a bluff home where the staircase sits between the living space and the water, the difference is significant.

Close to Commencement Bay we specify for it from the outset, using durable steel with appropriate finishing, non slip treads, and marine grade hardware. Ordinary fixings corrode in salt air well before the structure does, so the fixings are where the specification budget matters most.

In a renovation it often works very well. A minimal steel and timber stair set against original craftsman or Victorian woodwork reads as a deliberate contemporary intervention rather than a clash. The main practical consideration is the existing opening, since period houses are rarely square and the structure around the stairwell varies a great deal.