Attach wood stud to galvanized square tube

[TH-huset]

Hello, I have a floor joist that I am going to lay over a frame of galvanized square tubing.

The frame is made of galvanized steel and with 60cc, which means I want to attach the floor joists directly on top of the steel. I was considering if I could take proper wood screws, maybe Frans wood screws, make holes through the steel from underneath and then screw up through the steel into the joist. However, it feels like I could easily deform the beam if I pull too hard, which I definitely don't want to do.

Another option I had was to weld loops onto the frame that I screw the joists into, but I don't know how well and rust-proof I can weld in galvanized steel.

It would be great if someone here has a good idea for how I can proceed!

 

[Tomtom79]

What are the dimensions of the square tubes and floor joists?

 

[TH-huset]

What are the dimensions of the square tubes and floor joists?

The floor joists are 45x120mm, and the square tubes are 45mm wide and vary in height depending on where they are, but between 50-100 mm.

 

[Tomtom79]

Welding in galvanized is primarily outdoor work, as some nasty gases are produced. Maybe even proper respiratory protection is needed.

I'm considering what forces you want to be able to take up with the attachment. You don't want to drill large holes in the square bars so that they get weakened either, right? I'm thinking a type of u-bolt or whatever it's called might work? However, it won't be free if you want it to be somewhat affordable?

 

[TH-huset]

Welding galvanized is, first of all, outdoor work as it produces some nasty gases. Maybe even proper breathing protection.

I'm considering what forces you want to absorb with the mounting. You don't want to drill large holes in the square bars that would weaken them either? I'm thinking something like U-bolts might work? However, it won’t be free if you're aiming for something budget-friendly?

Yes, I’d prefer to avoid welding, I'm not exactly a master welder either

And what you say about making holes sounds very sensible. I've been thinking about U-bolts, but I don't understand how to properly secure them. The problem is that I have a finished floor structure with the floor laid on top and subflooring, etc., underneath.

 

[Paradis-Oskar]

Hello, I have a floor joist that I need to lay over a frame of galvanized square tubing.

The frame, as mentioned, is made of galvanized steel and with 60cc which means I want to attach the floor joists directly on top of the steel. I was wondering if I could use sturdy wood screws, maybe French wood screws, drill holes through the steel from underneath and then screw up through the steel into the joist. However, it seems like I could easily deform the beam if I tighten too hard, which I definitely don't want to do.

Another option I had was to weld loops to the frame which I then screw the joists into, but I'm not sure how well and rust-proof I can weld in galvanized steel.

It would be great if anyone here has a good idea on how I can proceed!

Place a batten on top of the square tubing and attach it with wing screws? Then you can attach your joists to it.

 

[TH-huset]

How do you think about the wing screw?

This sounds tempting but I would like to keep the beam under the entire floor with no air in between. But it should be possible to solve by laying wood on top of the entire frame.

 

[Paradis-Oskar]

How are you planning to use the wing screw?

This sounds tempting, but I would like to keep the beam under the entire floor and not have any air in between. But this can probably be solved by placing wood on top of the entire frame.

You thread the wing screw through wood and into the steel.

https://www.optimera.se/bygghandel/...-och-b/vingskruv-wingdril-c4-4-8x50-006586903

 

[TH-huset]

The wing screw is threaded through wood and into the steel.

[link]

that was a very nice little screw, amazing what you can learn!

Would it be possible/suitable to screw in an angle bracket with these screws and then screw the floor joist into the angle brackets?

 

[Paradis-Oskar]

it was a very nice little screw, amazing what you learn!

Would it be possible/suitable to screw in an angle bracket with these screws and then screw the floor joist into the angle brackets?

Yes, it certainly is.

If you're going to attach an angle bracket to the square tube, I would have used a drill screw instead.

 

[TH-huset]

Yes, it really is.

If you're going to attach an angle bracket to the square tube, I would use self-drilling screws instead.

that sounds good. Do I need to think about rust protection? I'm thinking that when you make holes in the galvanization, it might be easier for rust to attack the screw holes. Is there a way to counteract this?

 

[Paradis-Oskar]

that sounds good. Do you need to think about rust protection? I think that when you make holes in the galvanization, it might be easier for rust to attack in the screw holes. Is this possible to prevent?

Now I don't know in what environment this will be located, but I can't imagine it being corrosive? I wouldn't worry about it. The screw makes precisely the hole needed in the steel, and it should be sufficiently tight. Otherwise, there are drill screws with washers and seals if that feels better.

 

[TH-huset]

Now, I don't know in what environment this is supposed to be, but I can't imagine it being corrosive? I wouldn't worry about it. The screw makes exactly as large a hole as needed in the steel, and it should be sufficiently tight. Otherwise, there are drill screws with washers and sealing if that feels better

well it's going to be outdoors, but it's under the whole house anyway, so a sealing washer is probably a good idea!

 

[Rickard.]

Cold impact on galvanized steel hardly affects the rust protection at all, can't remember what it's called but the coating protects even if it is removed on small areas (sawing, drilling, scratching).

However, galvanized doesn't like significant heat, e.g. from angle grinders and welding.

 

[TH-huset]

Cold impact on galvanized steel hardly affects the rust protection at all, can't seem to remember what it's called but the coating protects even if you remove it on small areas (sawing, drilling, scratching).

However, galvanized doesn't like significant heat, for example from an angle grinder and welding.

okay, that was good info so the coating is more than just on the surface?