Those are "toggle bolts".
I try to avoid them at all costs.
They require a large clearance hole to install, and are a single use item.
"Molly Bolts" have a stamped steel cage around the self contained screw that expands and grabs the back side of the drywall when snugged up.
Lighter duty than toggle bolts but very useful for hanging full length draw drapes for example, and they are reusuable.
Lew
I'd forget the Lee Valley stuff and build an exposed cleat at least 8" high with a reverse 45 on top which then gets glued to the dry wall.
Using a large cleat will spread the load.
Probably require some time back on the drawing board, but worth it.
Lew
When you hang doors, always assume such a use.
Moonpie.... errrmmm.... maybe I shouldn't elaborate. ( but it had to 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
See? A VERY solid warning from one of our contributors. THIS is what makes the Wreck great. In real life contractor work-----> always assume the worst.
The ones I use have two spring-loaded wings that deploy after insertion.
So whatsitgonna be? A pop and sub or a soda and a hoagy?
Down here it usta be Sody Water.
I would have loved to have done that, and was going to to begin with, but they decided they really didn't want the mantle to be thicker than
4", and swore up and down they would never put anything heavy on it. They were also sure the studs were wood, until I insisted they verify with the builder.Oh well, maybe I'll suggest they hang it from the cathedral ceiling with very long wires....
Bob
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.
If you use the French cleat(s) with as many screws into the studs as you can get with self tapping screws, and also fastened to the sheetrock with "toggle bolts" in between the metal studs, AND, if possible, some construction adhesive to bond the back of the mantel to the drywall, you should be in pretty good shape.
Even without the construction adhesive, and providing all your screws prove to have a solid hold, my estimation from your description thus far is that you'll be just fine.
Will the client buy into the idea of the cleat being an architectural item that serves as background for the mantle since it would be larger than the mantle?
Lew
Well, that's exactly what I was thinking, and I think they would. A nice, matching cleat visible behind and below the mantle itself could actually look OK and be a pretty good solution. The back of the thing is recessed 1/4" to accommodate the Z-clips, as is the back edge of the bottom, but I could fairly easily build up the back edges of the top and sides by another 1/2" to shroud the cleat, maybe in walnut or some other accent wood.
This can definitely be saved...I think...
Bob
Have fun
Lew
I built a kitchen table, per request of a dear client of mine, which protruded 8 feet from the wall of her kitchen, no support, and 28" wide. It became a torsion box, Baltic birch and WEST epoxy. The anchor inside the wall was a simple doubling up of baltic birch.
*I* figured, that if that stuff was good enough for Mosquito bomber, it was okay for my application.When *I* sat on the end of that table with my ample weight, the downward deflection was somewhere between 3/8 and 1/2 inches. It was only 3" thick.
I luuuuuv torsion boxes.
Moment of Inertia (I) = (B)(H^3)/12 + 1/2(A)(D^2)
Moment of Inertia is your friend and easy to increase with a torison box.
Lew
I used 1/2" BB all around, but I could have used 1/8" for the skins.
There is a reason they're called "door skins".
If you can read a newspaper thru them, they are probably thick enough.
Lew
Well, as an update for them what's interested, I'm going to attach a wide cleat to the wall, glued, screwed, toggled, etc and hang the mantle on that. The twist is that the visible edges of the cleat will be bevelled, and the cleat will be painted same colour as the wall. That way, rather than looking like a piece of wood fastened to the wall, it will look more like wall feature. It will aslo be much easier to hide the bolt and screw heads, as they will be countersunk, filled, and painted.
Bob
Sounds like a reasonable solution to me.
-- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
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