Granite support over half wall - Contractor Talk - Professional Construction and Remodeling Forum

mullaman · 04-01-2009, 10:25 PM

I'm doing a job that involves taking a non-load-bearing wall down to 45" (2x4) and installing a granite countertop on it. I recommended either using 3/4 plywood underneath or corbels to support the 12" overhang on the one side. It is designed to have 12" overhang on one side and 4" on the other. Problem is the customer does not like the corbel idea and is worried about seeing the plywood underneath. Any suggestions on how I should go about supporting it otherwise? Thank you.

Kgmz · 04-01-2009, 10:45 PM

Is this half wall going to be supported at both ends, and by what?

Or is it a hole in the wall which will have full length studs at the ends supporting it?

Supposing it is a hole in the wall with support at the ends, even the plywood isn't going to cut it. You will have a 3 to 1 leverage ratio with a 12" overhang only supported by a 4" wall. Even if it is screwed down well to the top plate, whats going to hold the top plate down. And even if the top plate is screwed or lagged down, I wouldn't risk it something is going to come loose.

If they absolutely don't want any corbels or other type of support and want a thin look. Then one way would be to support it with steel plate with welded channel at the ends running full length down and bolted to a few studs.

orson · 04-01-2009, 10:52 PM

I would ask them if you have a wish in one hand and pooh in the other then what do you have? OK, I wouldn't really ask them that, but you get the point.

You are going to have to do corbels, you can reduce the number of corbels you need by doing both the plywood and the corbels. The plywood can stop 3 inches short of the edge of the granite and be finished on the edge and painted a dark color to make it disappear.

mullaman · 04-01-2009, 10:59 PM

Quote:

Originally Posted by Kgmz

Is this half wall going to be supported at both ends, and by what?

Or is it a hole in the wall which will have full length studs at the ends supporting it?

Supposing it is a hole in the wall with support at the ends, even the plywood isn't going to cut it. You will have a 3 to 1 leverage ratio with a 12" overhang only supported by a 4" wall. Even if it is screwed down well to the top plate, whats going to hold the top plate down. And even if the top plate is screwed or lagged down, I wouldn't risk it something is going to come loose.

If they absolutely don't want any corbels or other type of support and want a thin look. Then one way would be to support it with steel plate with welded channel at the ends running full length down and bolted to a few studs.

The wall is supported at one end - the other is and entry into the kitchen.

Thanks for the reply I appreciate it.

mullaman · 04-01-2009, 11:07 PM

I was thinking about using steel L brackets 1/8 - 1/4" thick, fastened to the studs. I am worried about supporting the bulk of it underneath though.

747 · 04-02-2009, 01:52 AM

Corbels or tell them no to slab granite they will have to go with granite tile.

AtlRemodeling · 04-02-2009, 04:39 AM

If the HO does not want corbels, can you use a decorative leg (s)? If that does not work you could use a double edge on the granite to hid your support, although I would use more than 3/4" plywood.

No matter what, I would explain the risk of the granite breaking if not properly supported. Let us know how it turns out.

rbsremodeling · 04-02-2009, 06:11 AM

Why do you need support on a 12" overhang?

A.W.Davis · 04-02-2009, 07:12 AM

Quote:

Originally Posted by rbsremodeling

Why do you need support on a 12" overhang?

Probably because its on a pony wall.

mullaman

Typically if an island where to have a 12" overhang it wouldn't be necessary to have corbels, or a post on each corner.

But for a pony wall, and IF it was one of our remodels, I would recommend to make it an 8" overhang set on 3/4" 10 ply- plywood. We have even routed steel into the subtop for extra support. You can tell your client to get over the worry of seeing plywood underneath, its mandatory to have a plywood subtop for granite. We always stain or paint the underside of the plywood on granite overhangs

VBuilt · 04-02-2009, 10:37 AM

I would of course be concerned with the stability of the half wall- not just down but back and forth so to say.

Insofar as supports/corbels, I did a summer home with an interior designer that insisted on a 20" piece of 1 1/4: glass x 8' long as a "mantle" over a gas fireplace insert. He isisted that it looked as close to floating as it could.

As I recall (it was about 17-18 years ago) I had 18" solid square steel stock welded to the side of a mounting plate. The plate was 5" (2x6 exterior wall) by 12" with bolt holes drilled. The plates were thru bolted to the studs (used four of them) with the square stock protruding out to support the glass.

After the finish work I had square brushed nickle "sleeves" with a capped end to slide over the steel support stock sticking out and set the glass on it.

mullaman · 04-03-2009, 08:18 PM

Thank you everyone for your responses and input, much appreciated. We went with 3/4" plywood and 10"x10" corbels. I beefed up the half wall by adding a couple extra studs and a 4"x4" to support the corbels. Also lagged the free end of the wall underneath from the basement to the joists. Glued the plywood down and secured with 3" deck screws. All in all it looked good and felt solid. I will see if I can load a pic.