retrofitting corbels for granite bar?

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Old 02-18-16, 10:21 AM
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retrofitting corbels for granite bar?

Hi all,
I have an existing 94"x16" granite bar that overhangs by 9". I'm not sure how the previous contractor installed it, but it is starting to drop towards the overhang. I would like to install corbels for aesthetics and weight bearing. What would be the best and most cost efficient method of installation? Do I need to drill through the corbel to bolt it to the frame? I viewed some products on federalbrace.com, but they seem to be decorative. I'm not stuck on corbels if there are alternatives. Name:  IMG_0195.jpg
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It is a 2cm countertop, supported by plywood.
Thank you for any help.
 
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Old 02-18-16, 11:31 AM
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The picture isn't clear. Is the whole bar settling causing the surface to have a slope? If you put a stream of water will it go to one side? Or is the granite slab in two pieces?

I suspect the wall is settling or the supporting plywood at the top just under the slab is not properly fastened. You should not need to provide support from underneath.

However, if you do want to you will need to use a masonry drill and drill holes into the underside of granite to accept a plastic screw anchor. Depending on the type of support will determine how many and what size.

I have a similar bar type are with a granite top with an overhang of 13". However the open end is also fully supported with an open cabinet.

 
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Old 02-18-16, 04:14 PM
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Norm,
thanks for the reply. I apologize for my delay, but I've been working on the house. The bar is one solid slab with no support, it is leaning down towards the unsupported portion, which is the greater portion of its width. I'm afraid that the bar will just fall off one day. I intend to use corbels as load support. What I'm inquiring about is whether I should drill through the corbels so I can bolt the corbel to the wall studs, or if there is alternate method using some fancy metal bracket that can fit behind said corbels. I've seen the "invisible brackets" everywhere, but I cannot remove the bar, so it must be a retrofit job. Thanks again for any help.
P.S.- the wife is not keen on any open cabinets for support, as we want to use it as a place to congregate or eat.
 
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Old 02-18-16, 05:28 PM
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Since you can't "Lift up" the corbel to install using the hidden brackets then you need to drill through them and attach to studs. I don't see that as a problem. You could use shelf supports like these

but they are not very decorative but they are almost hidden.

What you will want to do is using something like a 2 x 4 x slightly taller than shelf height and wedge it against the outside edge of granite shelf and gingerly (don't crack it) force it up until it's level (use a torpedo level). Or if you can get access to the under side of where it sits on the wall use thin shims to bring it up to level. You can gently hammer the wedges in with less chance of damage to granite. Leave the wedges in if you want. Nobody can see them.

Then use a fairly beefed up corbel that will give you plenty of room to drill a hole all the way through without cracking or sliding out the side. Use a hefty wood screw or lag bolt and attach to studs in wall. You don't necessarily need to attach to the underside of granite slab. You could just let it sit on the corbels.

If you bore a large hole in the corbel then you can use a steel washer to slip inside the hole then the screw or lag bolt and bolt to wall. You can plug the hole in the corbel using wood caps or plugs found in any hardware store.

If you want to attach to granite slab use a small diameter masonry drill and go into slab from underside about 1/2 to 2/3 into it. Use plastic anchors and then just a wood screw through the corbel and into the slab. Most dishwashers are attached to the underside of granite slabs in this manner.
 
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Old 02-18-16, 05:39 PM
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I took a second look at you pic on post #1. Is the extending sections directly below the shelf a wood trim or is it a wallboard molding before it thins down to the actual wall. That could present additional problems. If it's wood trim I would remove it, install corbels and then re-install around the corbels.
 
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Old 02-18-16, 06:40 PM
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Its been commented on but to emphasize, you will need to locate the studs and place the corbels directly over a stud. This will limit where the corbels can and cannot be.
 
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Old 02-21-16, 12:23 AM
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The trim under the counter may be a 2x4 - looks about the correct dimension and covered with drywall. If so you will have plenty of 'meat' to screw into. I would use a bottle jack and a length of 2x4 under the counter to carefully jack up to level, then use some steel angle brackets to hold the counter level. Use epoxy of Gorilla glue on the underside of the vanity to hold the brackets in place if need be (instead of drilling into the granite) and screw the bracket to the whatever the blocking is at the top of the wall. If you create a gap, while leveling, run some 3/4 round or trim to cover it. Paint the brackets an 3/4 round to match and you will never notice it. The brackets need only be 3" or so, small enough to not hang below the blocking.
 
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