WOOD TREADS AND RISERS ON FORMED METAL TREADS AND RISERS

Archive of Older Topics Archive - Product Discussions #6
1

I have a request to specify wood treads and risers fully adhered to 1/4 inch steel plate treads and risers form.

Never adhered wood to metal on stair.

I have not sourced an adhesive for bonding wood treads/risers to steel substrate.

Has someone out there solved this issue?

Please cloud the issue with facts.

Thanks,

Wayne

2

Wayne, we’ve specified wood treads and also stone treads (treads only, not risers) on formed steel plate subtreads. Rather than using adhesive, we mechanically fastened the treads using internally-threaded anchors embedded in the underside of the tread and countersunk flat-head threaded bolts, to fasten the treads through the subtreads.

I know this doesn’t directly answer your question, but we were more comfortable using mechanical fastening rather than adhesive.

3

I would think you would want to explore the difference in expansion between steel and wood, not only for thermal movement, but also for moisture as well. If your environment is not carefully controlled with respect to humidity, I would think you could see some buckling.

4

David,
Your suggestion is scathingly brilliant so I have recommended it.

Peter,
The interior environment is a high end fashions store in CA.

The detail provided shows the 3/4 inch thick treads and risers laminated to 3/4 inch plywood. I think this laminate will mitigate warping, cupping and bowing.

I suggested adding a sound reduction layer under the plywood same as I do for wood flooring in residential projects. Something in the order of 1/4 inch.

I think the joint between the tread and riser should be doweled, or use biscuits or pocket screws to mitigate separation.

5

Wayne,
Contrary to your expectation, bonding solid wood to plywood will guarantee warping. The two materials don’t behave alike with changes in moisture content (humidity.) I would use Dave’s method of attachment, but the holes in the steel plate should be oversize or slotted to allow the wood to move. The bottom edge of the risers should be attached to the backs of the treads, and the tops can be secured to the tread above with a loose tongue and groove.

Steve Taylor