Custom Spiral Staircase
This was, far and away, the most challenging piece of metal craft Somnus Customs has ever completed. From its inception to installation, it was done entirely in-house, and is currently the crown jewel of our project history! For a wonderful client in Stillwater, Minnesota, this custom steel spiral staircase is perched - overlooking the St Croix River. Typically, staircases like this are fabricated off-site in a controlled metal shop, and then lowered into place using a large crane or knuckle boom. If you’ve never been to still water, you should know that it rests in the St Croix Valley, and much of it is steeply graded and difficult to access; my client that requested these spiral stairs has a property that’s the poster child of this steep grade. The install location would be nearly impossible to access with a large crane or boom truck. On-site welding and installation was my only choice, and so I made a plan for it.
I grabbed inspiration from old victorian spiral staircases, utilizing the ubiquitous “holes” you see in old bridge and structural gussets.
A spiral staircase, in and of itself, is a wonderful statement piece. There is a time and a place for ornamental flourishes, but this wasn’t it…I wanted clean lines and strong metalcraft.
The center support column, off of which, EVERYTHING is perched is made of 4” schedule 40 pipe. This means it has a 1/4” wall thickness, and is a beefy 4.5” overall in diameter.
Even more impressive is the base plate! Made from 1/2” steel plate, and 3 feet in diameter, the bottom plate alone is a whopping 150 pounds! At 14’ long, believe it or not, I managed to place the center column using one extra set of hands and a two wheel dolly.
It made the most sense to install the staircase’s parts from the top down. I had a good idea of how the geometry was going to play out, but in a situation like this, where it was almost impossible to do a mock-up, and fixing mistakes is beyond a headache, I aired on the side of caution…and what do you know, the universe showed me a little mercy with a flawless fitup.
I’d never done a spiral staircase before, but there was nothing truly unique about any of the fabrication required, when compared to my experience…that is, except for the helical handrail. Rolling radii is an artform in and of itself. Even a regular circle, comprised of a flat radius, is tricky to get perfectly round. Knowing this, I wasn’t about to challenge a shop with the task of rolling a helix. Instead, I did a little guess-and-check in my 3d modeling program to determine what sort of radii I would need in order to make this handrail. About an hour of head scratching lead me to a 7 foot radius circle, chopped into 48” sections, could be “twisted” into the helix shape I’m looking for. I received one crucial piece of advice from another metal shop, and that was to fabricate the railing with it laying on the treads of the stairs. This is to guarantee it will match the exact shape and pitch of the steps. It came out beautifully.
A little spit shine and a coat of paint was the balance of what was left after the handrail and spindles were installed…once again, the universe smiled on me, and gave me a nice sunny day to reflect on the work I’d just finished.
A final walkaround of this custom spiral staircase.
