Fastening to metal studs

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Hi all,
I'm builing a cherry mantle for some friends, the floating type, made to be fastened directly to the wall above the fireplace. There are no sides, so no support from the floor. It weighs about 25 lbs or so. I had planned to use French cleats to hang it from the wall, but they just found out from the builder that the house is built with metal studs, and not wood as we had expected. Can you hang that much weight from metal studs, and if so, what sort of fastening system would be best? There are basically 4 studs along the length of the mantle.
Thanks,
Bob
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That shouldn't be a problem - then again, it depends on how much crap the owners put on the mantle. The weight of their stuff could easily exceed the weight of the mantel if there's a reasonable size shelf top.
You should use expanding metal anchors into the studs such as a Molly anchor or toggle bolt, and you might want to consider making the french cleat on the wall taller so you could get a couple of fasteners in each stud. You could also use some construction adhesive, but that's belt and suspenders and probably not necessary.
R
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giga wrote:

Sure. You could hang it from just the drywall too. ___________

You could use any sort of expanding fastener or just screws meant for fastening drywall to metal studs...there is very little "out" force, mostly it is "down".
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: giga wrote:
: > no support from the floor. It weighs about 25 lbs or so.
: Sure. You could hang it from just the drywall too.
The weight of the mantle is not what you worry about. You need to estimate the load of a 300 lb 6'6" guy leaning on it with his fore-arms. Or maybe two such guys. Or, worst case, someone standing on it to put the star on the top of the Christmas tree. If it looks big and solid and it's attached to the wall, people will assume that it can take load like a step-stool.
True story: A guy was making some pull-down stairs for a hay-loft, and asked my father to check the design. My father recommended beefing up a cross bar, and the guy asked why, since it didn't have any load on it. My father explained that sooner or later some guy was going to use it as a chin-up bar.
The day after it was installed, the guy was showing it to his neighbor, a big football player type. As soon as he saw the bar he jumped up and chinned himself on it.
--- Chip
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Chip Buchholtz wrote:

When you hang doors, always assume such a use.
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"giga" wrote in message

BEWARE: Mantles end up being the resting place of expensive "objects d'art" (if not for this resident, perhaps for the next) and because of this fact you may well be doing yourself a favor to "over engineer" ... you do NOT want any unpleasant call backs from "friends".
What material is the wall? This information is important to an effective solution.
Self tapping screws can be used into the metal studs, but, depending upon the wall material, I would also routinely throw in a few molly bolts in between the studs for the wall half of the French cleat.
As others have mentioned, and depending again upon the wall material, a bit of construction adhesive would also add to the "belt and suspenders" approach, which is certainly justified in this particular situation due to first above.
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what would the adhesive do attaching the cleat to drywall? the paper isn't very strong, and that's all you're gluing to.
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"charlie" wrote

How do you know the OP is attaching to drywall?
Nonetheless, much of the "fastening" of chair rails, wainscotting paneling, to drywall is done with at least some construction adhesive. Later down the road, when trying remove same, you gain a quick understanding as why it is not a bad idea to include in it in a "belt and suspenders" approach. :)
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"charlie" wrote:

The adhesive increases the surface area of the cleat in contact with the drywall.
The increased surface area reduces the load/square inch on the joint.
Lew
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Have you ever tried to suck the paper off the wall before? ;~)
The strength would be in the huge adhesion area and while not sufficient by itself would add considerable stability to other fasteners. I have seen large pictures hung on those removable 3M adhesive hook strips and those do not cover much area by comparison.
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wrote:

One important advantage is that a fixed item doesn't pry up its fasteners one at a time as it flexes. I've used construction adhesive and masking paper to make a tight conformation of a cleat to a wall: tape up the masking paper to protect the wall, put down a bead of glue on the cleat, affix the cleat over the paper, then trim any paper away when it's dry. It's easier than coping an oak board to a plaster wall... With all the gaps filled, the board and wall move together.
Wood around screw threads can crumble with shock: glue can be strong enough (a mantle cleat can have square feet of glue area) to hold normal loads, then when a shock comes along the screws get only a momentary load. The screws could work loose under sustained load, we all see this in doors with poorly mortised hinges. OK, it is a small effect, but wood DOES give way under sustained stress that a strong metal screw is likely to apply.
It's advantageous, where possible, to use large contact areas where wood is stressed; a lap joint with dowels holds more shear than the same joint with screws, because the dowel surface area in contact with the wood is much larger than the screw cross-section.
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"Swingman" wrote:

If I were doing this job, shear load is not going to be a problem; however, cantilever loading could be.
As someone suggested, the wider the French Cleat, the better. 6"-8" would be a good starting point, 12" if there is room.
I would attach this cleat using #14, coarse thread, self tapping, S/S, flat head, sheet metal screws (At least 2-3 per stud) along with construction adhesive.
Just you're basic belt and suspenders design approach.
Allow the adhesive to cure 10-14 days before using.
Lew
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"Lew Hodgett" wrote

Precisely ... and the width of the mantle from front to back is an important component of this particular force, and, like the wall material, is unknown at present.
Nothing like trying to offer solutions when most of the important factors are unknown. :)
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It also depends on the gauge of the metal stud. I hang entire rows of wall cabinets on metal studs with toggles if they're thin gauge studs and self tapping screws if we're dealing with thick metal... even then we pre-drill with a 1/16 bit. The load on cabinets is more shear, and Lew is right about the load being very different if the shelf protrudes from the wall and creates a cantilevered load. One brass statue and Swing's caution should be heeded. ( Or one arm of my ex with a beer in her hand leaning on it...MUCH more serious than a brass Rodin.)
Toggles. When in doubt, I always use properly installed toggles. The plastic expanding ones will cut themselves on the inner edge of a metal stud hole, so use metal ones. This building doesn't have a bd-ft of wood, to screw into, in it: http://www.marinervillage.ca/photos.htm We have installed many kitchens in here and toggles are my friend.
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(suite 114 is one of our jobs)
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"Robatoy" wrote
Toggles. When in doubt, I always use properly installed toggles. The plastic expanding ones will cut themselves on the inner edge of a metal stud hole, so use metal ones.
Interchangeable terminology for a "molly bolt" down here in Tejas ...
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insertion.
So whatsitgonna be? A pop and sub or a soda and a hoagy? <G>
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"Robatoy" wrote

An R'erC and a moonpie, thanks!
;)
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do with da girlfriend, walking on the beach at night.. then she'd check the laces on her sneakers....alas I said too much already.......)
Molly Bolts, eh? Yes, Those flare out like a star and are some tough. One use only. The toggles, you can take out the screw and have the wing part fall down and re-insert the a new toggle. Lew is right about them being a sloppy hole, but used in conjunction with a french cleat, they are very solid. Long cleats have the problem of walls being not-flat.
r
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wrote:

insertion.
So whatsitgonna be? A pop and sub or a soda and a hoagy? <G>
Down here it usta be Sody Water.
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