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

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

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

(OP)
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?

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

Why not just use wood screws in pre-drilled holes in the plate.

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

(OP)
That was my suggestion but they wanted to see if it was possible without pre-drilled holes.

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

Seems like predrilling would be a lot easier/faster to install. On a side note, how are you guys defending 3/8" steel plates? With a central stringer we have always used 1/2" min at treads and 3/4" at landings.

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

I would tell the client that his idea is silly...maybe not in those words. You need a wood screw, and that won't drill through 3/8" steel.

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

Tek5 is the only self drilling fastener for 3/8" that I know of, but I know of no load capacities in wood. They are likely more than than adequate; just use a aimilar sized screw for load capacities. It's silly not to pre-drill the holes.

Dik

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

jdengineer,
You don't need a plate that thick. The wood will carry the load.

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

Can't think of anything but a sarcastic remark so I am out.

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

for an 1/8" plate use Tek3's... but, still not a good solution.

Dik

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

Quote (dlk)

for an 1/8" plate use Tek3's... but, still not a good solution.
Teks don't work well going into wood. I think the debris coming off the drill point fouls ups the threads.
I have tried it personally on a project.

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

XR... as I noted in the Tek5 comment... I have no idea of what the capacity is in wood... they're not meant for it... but, they are the only fasteners that I know of that will self drill thick material... as I noted... silly idea... right out of Monty Python Tech...

Dik

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

Dik:
Silly ideas and details (dare say, stupid ideas and details) haven’t stopped a lot of Archs., clients, owners, and many engineers too, from doing really dumb things. Remember, most of the former aren’t engineers and too many of the latter aren’t either. They have a computer program, and that’s about all, and that hardly makes them thinking or knowledgeable engineers on any given problem. The client probably got suckered into buying a box of those screws, they didn’t work too good for the first project, so now he wants to use them up. Flat headed screws? Are they self counter sinking too? Drill and countersink the damn plates. A fab shop/machine shop will drill and countersink the holes faster than the time wasted debating here. Then use real wood screws that you can count on. It will cost the client something but nowhere near the time wasted farting around with his original idea, on the job site.

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

(OP)
Thanks for the input, I will insist on pre-drilled holes.

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

I wouldn't bother with countersinking the screws into the steel. Flat head screws will be under the tread, so why would they be objectionable?

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

2
The main issue is that if the screw is threaded into the steel and the wood, it cannot pull the two together.

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

Try SFS Intec (I have no connection to them, but they have and make connections). Self-drilling screws for wood-steel connections.

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

I think anyone who tries to use self drilling, self tapping screws in 3/8" steel will soon realize why it isn't a great idea.

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

Hokie... it may even be considered a 'dumb' idea...

Dik

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

Yes, Dik. I did already say it was silly.

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

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.

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

Assuming these are interior stairs, use a structural adhesive

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