Floating stairs: how they are actually built
Floating stairs look effortless, which is the point, and that appearance is produced by a lot of steel doing hidden work. Here is what is behind the treads people admire.
There is no such thing as unsupported
A floating stair is supported either from a single central spine stringer, from the wall alongside, or from a stringer concealed within the wall build up. The tread appears to hang in the air because the support is inside it or behind the plaster.
Wall supported cantilevered treads are the most demanding version. Each tread has a steel arm embedded into a structural wall, and that wall has to be capable of resisting the bending force from a person standing at the outer edge. A single skin of block will not do it, which is why this design is settled with the engineer before the wall is built.
The spine stringer option
A central spine is the more common and more affordable route. A heavy rectangular hollow section runs up the centre of the flight and each tread is fixed to it with a concealed bracket. The spine has to resist twisting as well as bending, so it is considerably heavier than it looks.
This version can be installed into an existing house without rebuilding walls, which is why most Dublin retrofits use it.
Tolerances and finishing
Because nothing is hidden by a closed riser, every error is visible. Tread spacing, level and projection all have to be right to a couple of millimetres, which means laser measurement on site and careful set out in the workshop.
Welds are ground and dressed so the finished steel reads as one piece, and the powder coat is chosen to match the interior scheme.
Guarding still applies
Open riser and floating stairs are allowed in Irish dwellings but still need compliant guarding, and the 100mm sphere rule applies to the gaps between treads as well as to the balustrade. Glass balustrade is the usual solution because it preserves the visual lightness.
We design the guarding as part of the stair rather than adding it later, so the fixings are built in and nothing is drilled into finished steel on site.
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Common questions
Need this done properly? Talk to the workshop.
Send us drawings, a sketch or a site photo. We come back with a fixed price and a firm lead time, usually within one working day.