Installing spiral stairs on tile floors
You can install spiral stairs on tile floors two ways. It depends whether the tile is in place before you start the spiral, or whether the tile will be added later.
In the first instance the spiral stairs can be placed directly onto the existing tile floor. Figure 1 shows the basics of placing spiral stairs on tile. (Note: throughout this article “floor parts” refers to the spiral stair parts that contact the floor.)
The hardest part of this installation is drilling through the tile surfaces to anchor the spiral to the flooring below. Numerous websites demonstrate the best way to do this. The type of tile, ceramic, or the much harder porcelain, will influence your choice of drill bit. The flooring under the tile substrate will determine the best fasteners to use.
Spiral stairs on tile floors that are not yet in place
Installing the spiral stair before the tile is down is an easier installation because you don’t have to drill through tile. So if you are already laying the tile, leave an open area in the vicinity of the spiral stair. Install the bottom tread floor parts on shims and you can tile right up to and under these parts.
Figure 2 illustrates the bottom tread floor parts sitting on shims. You can fasten the spiral to the bottom floor before the adjacent tile is installed.
Plan the shims to be 1/32” thicker that the tile. This clearance allows the rough-cut tile edges to slide under the floor parts.
Keep in mind the finished bottom floor surface will the top of the tile once it is installed. In this case the bottom tread rise should be 1/32” less than the height between other treads. You can arrange this method, or something quite like it, with your spiral stair manufacturer.
Spiral stairs on tile with irregular surfaces
What if your spiral stair on tile installation may involve an irregular surface, such as with slate or other stone? Figure 3 depicts this installation and what you need to look out for.
An extremely rough surface could make things more difficult. The first challenge would be to determine the actual floor level.
Then you have to support the bottom tread to sit at this level. Depending on your preference you could do this with shims, pre-placed grout, or a combination of shims and grout. Figure 3 gives examples of each method.
And finally, you need to drill through the stone and use fasteners long enough to grip the flooring below the substrate.
One thing that makes all of these tile installations worthwhile though is that a spiral stair on tile makes a very handsome installation.