granite counter top question - Contractor Talk - Professional Construction and Remodeling Forum

Project53 · 10-31-2006, 02:36 PM

I have someone who wants a large island. Its 8' long and wants a granite counter top/or silestone. They want a 15" over hang, only on the back...so it's like a bar type thing going on.
were talking about useing stock cabs here..18" then 36" for the sink, 24" open for the dishwasher then another 18" for the end.
Question is , can I just put the granite on top of the cabs with 15" over hang..or do I need to put a plywood base down?
The big problem I see here is if they have 10 people leaning on the 15" over hang...it may move.
I don't know what type cabs he wants to use, but my guess is pretty much store bought stuff, which means there MDF sides and such and no good way to attach the counter top. So figure you have 24" sitting on the cabs...but that 15" overhang....makes me think twice. Any Ideas on this?

Mike Finley · 10-31-2006, 04:07 PM

2 corbels.

Bob Kovacs · 10-31-2006, 04:48 PM

In most cases, if you've got 3/4" granite with an applied edge buildup (to make it look like 1 1/2" thick granite), you need a 3/4" subtop anyway to keep the granite from laying over the top of the cabs. Especially with the void over the dishwasher, I'd put a 5/8" or 3/4" ply subtop on the cabs (ask your granite vendor what they need), and then install at least two (preferably 3) 10"-12" corbels under the overhang. Anything less and you're risking having a big problem.

If you don't like the corbel look, you can slip a piece of 1/4" or 3/8" thick steel plate under the stone instead of the plywood. Of course, that may also crush the cabinets....lol.

Bob

Hammatime · 10-31-2006, 04:48 PM

I'm assuming you would be building a half wall to attach the cabinets. If that is the case, than use 2 corbels if you want as Mike said. If you are not building the wall the corbels will have no effect, as they would be attached to the back of the cabinets. But if you are building the wall then you would have about 28" of support and that should be enough so you don't have to use the corbels if you do not want them.

Nick H · 10-31-2006, 05:19 PM

I did a very simlar job a few months back. It was an island about 5 feet long made out of a couple of standard kitchen base cabinets screwed side by side. The granite was an inch thick and overhung on the back about 13 or 14 inches. The cabs were on plastic legs and it was way to wobbly so i basically "wrapped" the sides and backs in 3/4 ply and then clad that with 3/4 oak to match the kitchen, this all extended to the floor so that it all sat solidly on the ground. When all that was done the whole thing was very heavy and there was no chance that it might tip or move but just to be sure I fixed 2x2 to the cement floor and screwed the cab sides into these ( right down low, almost invisible).
I've been back there many times doing other work and they've had no problems with it

CCBuilder · 10-31-2006, 05:30 PM

Any granite overhang that is 10" or more should have support. 10-12" you could probably get away with corbels or brackets. Over 12" a plywood support in combination with the supports is necessary. You may be able to cut the plywood to fit around your cabinets for the overhang so that you don't have to build everything up. This definately should be used in combination with supports though. You're right - the granite could crack without it.

Hope this helps

Nick H · 10-31-2006, 05:50 PM

I should say I just built up the cabs and had nothing to do with the granite, those guys came in afterwards and fitted it so I would guess they were happy with the overhang, its certainly down to them if there's a problem.

Project53 · 11-02-2006, 08:28 AM

Thanks guys. The half wall sounds the best and will give the best support. The granite guys don't want to see more then a 12" overhang anyway. So that should work fine.