Round Wood Spiral Staircase

[ziggy]

 

April and I built and installed this roundwood spiral staircase over the last five days. The design came from Tom Cundiff, who instructed us on the layout over the phone and in person during our last Timber Frame Workshop. It took us a while to fully grasp the layout and the flow of things, but once we fully grasped the idea, it went fairly smoothly.

The center post is black locust, perhaps 10-12" in diameter at the base. Very dense.



The layout was largely dictated by a daisy wheel with 14 points, drawn on the floor itself before the post when into position. The lines of the wheel indicate the angle of the stair risers,  but not necessarily the exact position of the mortises themselves. We had some wiggle room there.





The risers themselves (3x5 oak) have 6" long tenons (ideally, when we could drill that deeply), and are seated in the post mortises, and pegged with two 1" pegs.







We were very impressed with WoodOwl's Tri-Cut Ship Auger bits for drilling into the locust.



The steps are storm-felled elm, lovingly sawn up by Tom with a live edge intact. The step stock ranged from 14 - 18" wide, and we clamped the stock in position to the riser to see how and where to make our cuts to determine the shape.



Once cut, April used a gouge to create a beautiful, non-slip surface texture. Land Ark (Heritage Natural Finishes) Concentrated Finishing Oil was our sealer of choice here.

Two 4.5" GRKs fix the tread to the underside of the riser above. Ideally, we will go back some day and shim between the treads and risers where need be, and hide some screws in the top surface of the tread into the riser.







We are very happy with the final product. I think the hours of awkward drilling and mortising paid off.

[ayerwood]

Very cool project.  Thanks for sharing.

[ballen]

Great look!
2 quick questons...
The 6" tenoned risers hold the weight of each step?
Any railing codes?
Thanks

[jueston]

it looks incredible, when you climb the steps is there any deflection or creaking? do you plan on installing a railing?

[classicadirondack]

boy, oh boy; oh boy; oh boy

[Holmes]

That is a lot of work and very well done.  In my 45 years in home construction I have seen 3 of these stair ways built.  They are rare   Great job.

[ziggy]

ballen: Correct, they hold the weight. We don't worry about codes in northeast MO, as there are none to speak of... though we imagined it would be nice to have a railing on there some day anyway.

jueston: The steps make no sound. There is some slight movement in a couple of the risers, but nothing that you can feel yourself while walking up them. It could be that a couple receive some supplemental support (discreetly tied into surrounding framing) at some point, but things are quite solid.

Thanks for the all the comments!

[samandothers]

Great job and craftsmanship.  Thank you for sharing your pictures.