Axial load of metal 20g DW studs?


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Old 12-13-17, 11:31 AM
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Axial load of metal 20g DW studs?

Hey.. did a search but nothing popped up.

What's the axial load max for a 20g 8' non-structural (drywall) metal stud? I cannot find a chart anywhere online that I can actually read and it;'s driving me nuts. Need to put about 600lb of stone on a durock wall and need to make darn sure metal studs will hold it.

Brian

edit: sry I mean the regular 3.5" version. Also would love to know the difference in the smaller ones too if anyone knows.
 
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Old 12-13-17, 11:56 AM
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I think that you found your answer even though your terminology may be off. Non-structural studs are not designed and rated for that kind of load. In fact a non structural stud isn't really designed to carry a structurally significant load. In reality we all know they can carry some sort of load but a lot depends on their installation. Often they (the studs) are not full length and are held off the top and bottom plate and secured only with a sheet metal screw or two which is less strong than the end of the stud bearing down directly onto the top or bottom plate.

In your case you need to look at how spread out the load will be. A 96" long wall with studs spaced 16" center to center has seven studs. Divide that seven into 600 pounds and the load per stud doesn't sound so bad at about 85 pounds per stud.

The off center load of your stone will try to twist the wall and it's weight will be trying to compress the wall, two different things. The studs are probably captured top and bottom by the top and bottom plate which really helps lock them in the in/out direction so I wouldn't worry about the torsional load/stress. And, since you're got the weight spread out over seven studs that hopefully is light enough that the typical four screws (two top, two at the bottom) can hold it.

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Axial load for a stud is a load along it's length. It's like placing a weight on top of your stud putting it in compression. It can also be in the other direction putting it under tension but either way the load is straight down the center of the member.

Torque would be a load off center that tries to twist your stud. This force can be trying to twist the stud side to side (like turning an axle or bolt) or in the other orientation trying to twist the stud out of the wall towards the stone weight.
 
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Old 12-13-17, 03:15 PM
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Non-structural studs are not designed and rated for that kind of load
I'm confused. I realize that if you cut the studs too short ( and leave a 1/16" or larger gap) that the load would rest on the screws, so I won't be doing that. You mention that they can't hold that type of weight, then go on to explain that they can...?

The literature for the stone I'm using mentions metal studs as a usable option, it just does not say what type. Also I've seen multiple situations like mine where people used them... I just don't know how safe they really are.

If I have 4 studs across a 60" wall (or even just TWO studs), would they not be ok with a 600lb load once properly framed in and reinforced horizontally? Does the stone/thinset/durock itself not bear a large portion of the load? I understand the point about torsion but also think that if a stone veneer wall is built plumb that very little weight will be at a forward angle pulling on the wall the way you describe? Hell I don't know. lol

If I can use them great, if I can't, then I'll deal... What other information about the situation would I need to provide to make it easier to answer one way or the other? Everything seems grey area or contradictory with these things. If it wasn't so close to the fireplace brick I'd just use wood and be done with it.. lol

Brian
 
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Old 12-14-17, 06:28 AM
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You went from an 8' wall down to a 5'?

You were asking because you could not find a specification or rated capacity. I said that they "are not designed and rated". That doesn't mean they can't do the job. It just means that the manufacturer doesn't claim a strength or working load. So, your on your own to look at what you are building to determine if it will work.

If you are attaching your substrate to the studs then the studs are carrying the weight. Yes, the Durarock has it's own strength but if it's being carried by the studs it's the studs bearing the load. If you put a 60lb bag of concrete on top of a ladder the ladder is supporting the load. If you pick up that 60lb sack of concrete and stand on a ladder the ladder is still supporting weight of the concrete... plus your weight. Even though you have strength yourself you and the concrete are being held up by the ladder.

In your situation more studs are better because the more you have the more the load is spread out. One or two studs I'd say "no" don't do it. With seven studs the load on each is pretty low and I'd bet you'll have no problem. Put in ten studs and the situation gets even better.
 
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Old 12-14-17, 12:28 PM
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It's (will be) an 8' wall floor to ceiling, I meant about 5' wide... sorry for the confusing post. I just meant to determine the amount of studs necessary in that width to support the weight. I think I'm a bit better now, I located some 18g steel studs rated for load bearing walls. Gonna use those instead of the 20g I had. I think they should be fine. Is it ok to mount some of the substrate (cement board) directly to the brick of the fireplace with anchors or screws? Thinking of all angles here...

Thanks
Brian
 
 

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