Metal Screw to Attach 3/8" Steel Plate to 3" Wood Tread 2

[TXEng-USA]

I am designing a "floating" staircase which utilizes a 3" solid wood tread on top of a 3/8" steel plate. The client would like to use a flat head self-drilling or self-piercing metal screw that they would attach from the bottom.

I have only been able to find screws that are certified for attachment of wood to steel when the head of the screw is in contact with the wood.

Is anyone familiar with a screw that is certified for the condition noted above?

 

[berkshire]

TXEng-USA
Why not punch holes in the steel tread plates for the wood screws in the shop before you assemble the staircase ?
B.E.

You are judged not by what you know, but by what you can do.

 

[Ron]

Assuming these are interior stairs, use a structural adhesive