Floating Staircases, Engineered to Feel Weightless

Structural steel, hidden. Most of ours run on a mono-stringer, a single heavy steel spine under the center of the treads, or on cantilevered steel embedded into a structural wall. The visual trick is that the support is inside the stair or inside the wall, so the treads read as unsupported. That is a structural steel problem before it is a design problem, which is why a shop that does both is the right place to build one.

In most cases yes on both. A floating stair changes how load moves through the structure, particularly with a cantilevered design that transfers into a wall, so it typically needs engineering and it falls under the permit for the work. We build from stamped drawings and coordinate with the GC and the engineer on the connection details rather than improvising them on site.

The same code as any other stair. Under the 2021 Washington State Residential Code, guards on the open sides of stairs must be at least 34 inches measured from a line connecting the nosings (R312.1.2), a handrail must sit between 34 and 38 inches (R311.7.8.1), and the guard cannot pass a 4-3/8 inch sphere on the open side of stairs (R312.1.3). Open-riser floating stairs get looked at closely on the sphere rule, so it is worth designing the guard alongside the stair rather than after it.

Floating stairs are the premium end of what we build, above glass and well above a standard steel railing. They are a structural assembly with a finish-level tolerance, not a railing. Most of our overall project range is $5,000 to $15,000, and a full floating stair typically sits above that. Send the plans and we will come back with a rough number rather than a guess.

Almost always an undersized stringer or a connection that was fit on site instead of measured. A floating stair concentrates load through very few points, so small errors show up as movement you can feel. We 3D-scan the opening with a Trimble X9 and cut on a fiber laser, so the steel arrives matching the actual space and the connections seat fully instead of being shimmed into place.