Corbel Over Tile

King of Crown

Alright, I have a change order, and the contractor wants corbels instead of cabinets in the bathrooms. Its a comercial. Steel studs boys and girls bathrooms. marble countertops weighing around 140#s a peice. I am milling the corbels out of 1" thick laminate pine, to go with the rest of the building.
My main problem is the tile guy has already been in, and put tile around the whole room. How would you guys mount these?

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RowdyRed94

Did the tiler use cementboard or drywall? Obviously wall stiffness is an issue so you don't crack the grout (and maybe the tile). How about adding some extra nuts & washers to regular toggle bolts to leave the head sticking out a half inch, then insetting keyhole plates in the back of the corbels to hang on the screwheads? Three or four per corbel would hold in the studs, I'd think.

You could also make some cleats to go across the wall, high and low. Screw them to the studs and notch the corbels around them.

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Clint - carpenter, coordinator, webmaster

clampman

I would pass on that job myself. I assume these slabs are 20" or so wide, and not very thick. To the weight of the marble you're going to have to add the weight of at least two boys sitting on the edge.

Designing with corbels will put the top fasteners in tension as well as shear, and unless those studs are structural steel studs, the fasteners will have little strength.

In addition, even flawless Carera has hardly any strength except in compression, and is usually supported all the way under it, right up to the sink cutout. Also most of the interior designers out there don't know the difference between marble and travertines, and most of the "marbles" I've seen are travertines. They will often fall apart just picking up a slab, and are composed of as much epoxy fillers as they are limestone.

If I couldn't talk them into columns at the front corners under some sort of rail, I'd pass on that job.

Good luck.

regards,

jimc

RowdyRed94

I'd guess they're "cultured" marble.

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Clint - carpenter, coordinator, webmaster

clampman

Even if they are cultured marble, attaching them with corbels will not work for very long.

No matter how your contract is written with the GC, as soon as some kid rides it down and gets cut up, the lawyers will be going after everybody, regardless of who was "at fault".

Not only are screws, mollies, and toggles insufficent for a leveraged load like that, standard steel studs are as well, and I doubt that even the structural studs used on commercial balconies would be enough to prevent severe deflection, even if the fasteners were welded to them.

I would still pass on that job. Sometimes the juice just aint worth the squeezing.

Regards,

jimc

RowdyRed94

That's probably good advice. Tile is easily repaired. Open the wall, fit two or three layers of 3/4" plywood where appropriate, and reinstall cementboard. Tile can be reset in minutes.

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Clint - carpenter, coordinator, webmaster

King of Crown

thanks guys.

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clampman

King,

Is this plastic marble or real marble? If real marble, I would fax the supplier and ask him how it needs to be supported. For example, what kind of unsupported span it can handle with kids sitting on it. And have him fax the answer back to you - and save the fax.

regards,

jimc

King of Crown

I live in Arizona.
They dont care. I beleive its cultured, but seriously, I've been talking with the company directly and they seriously didnt care.

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