Cherry stair treads, stability

quietude | Posted in Wood and Materials on October 28, 2006 01:38am

I am making cherry stair treads 32″ X 8″ in 8/4 stock. They will be attatched from underneath to a steel staircase. Only the ends will be screwed down. The plan is to dress them bone dry in the shop, then hit them with numerous coats of polymerized tung oil before installation. Should I be worried about significant cupping? (location is an old building in New York) Please let me know if there are variables that I should include or things that I can do to increase the stability.
luke

Replies

SteveSchoene | Oct 28, 2006 04:54am | #1
You don't want them bone dry, you want them at the approximate equilibrium value in their installed location. With the ends screwed solidly to the steel staircase you shouldn't have a cupping problem, though you might want to allow for some change in the width of the tread as seasonal moisture levels change.

Why polymerized tung oil? It's hard to apply, and while it offers a little more protection than the un-polymerized version, its not very abrasion resistent for a stair case.

I'd use one coat of BLO to enhance the grain and color and then top coat with a more durable finish designed for floors--most probably a polyurethane.

I do have another concern. Under the international Building Code (IRC) , residential stairs in most places (I don't know about New York but I doubt it is less stringent) would require any staircase to be at least 36" wide, and would require the tread to be at least 10" wide. (The maximum riser would be 7 3/4") Commercial building requirements would call for less steep stairs. There is also a problem if you are adding treads over existing stairs, since all tread risers, including top and bottom, must be the same height, with no more than 3/8" variation between largest and smallest. Regardless of the code, 8" deep treads could be dangerous.

quietude | Oct 28, 2006 05:35am | #2
Thank you for your advice. I appreciate the information and the concern. This staircase goes to a sleeping loft, and the backs of the treads are open so it is treated as a ladder. The staircase and the metal work were approved by architect/engineer and city. As per your suggestion I am looking into other finishing combinations particularly the sutherland wells tung oil/polyurethane set. Are there any that you would suggest particularly?

Edited 10/27/2006 11:12 pm ET by quietude

kage29 | Oct 28, 2006 08:17pm | #3
Very happy with the Southerland Wells as described on our floors.

quietude | Oct 28, 2006 08:21pm | #4
Thanks for the feedback. How long have you had the floors?

kage29 | Oct 28, 2006 08:25pm | #5
Red Oak circa 1930, refinished last year, kids etc.
quietude | Oct 28, 2006 08:27pm | #6
Thank you very much. I think that's what I will go with.