Not all spiral stairs are created equal

As a builder, one of my favorite projects, besides building indoor rock climbing gyms was building spiral stairs.  They are one of the few things that could possibly drag me out of retirement.  

The design was my own and I built at least 7 sets over the years.  Most of them were built prior to my moving to the left hand side of the country so I have very few pictures of the stairs–at least nothing digital that would make blogging about them easier.

I built one set here in Seattle, 25 years ago for people that have since become good friends.  When I was at their home a couple of years ago I asked them if I could come back and take some pictures–which of course they were gracious enough to let me do.

The stairs looked pretty much the way they did when I built them 22 years earlier–with only a small amount of wear on the treads–and some color change typical of all natural-finished wood.

Except for the spaces between the treads, and the way the handrails end, this set of stairs pretty much meets today’s codes.  Stairs I built after these had decorative pieces to reduce the spaces between the treads to less than 4.”

I have built these stairs out of 6/4 and 8/4 oak, 10/4 ash, and even 12/4 white pine.  The thickness was always relative to the diameter of the stairs and/or the species of wood being used.  They have ranged from 5 feet in diameter to 7 feet in diameter–one was even “S” shaped, which meant it had to have two center columns. 

Each tread is freely cantilevered from the central column, picking up only very incidental support from the balusters tied to the handrail.  The central column is solid wood.  Four threaded rods run from a steel plate that is bolted to the floor.  The solid blocks and treads slide down over the threaded rods which are then caped with another steel plate.  The nuts are tightened making the entire column and treads one rigid unit. After 22 years the stairs were still just as rigid as the day I cranked the bolts tight–indicative of virtually no shrinkage of the treads.

The most critical design element was the preciseness necessary in the spacer blocks.  If they were not of perfect thickness over the entire diameter the blocks, the spaces between the ends of the treads four feet away from the central column might be considerable.  This was complicated by my wanting all the blocks to be cut from the same boards so that the grain would match even while divided by the treads.

Like I said earlier, I really enjoyed building these stairs and they are perhaps one of the few things that would drag me out of retirement.  As the years go by however, that seems more and more remote!

By Charles Buell, Real Estate Inspections in Seattle

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