Granite Counter Support
Ryan Klak is having a gorgeous granite counter installed in his Cypress, TX home. The trouble is he's spotted a sag in the granite and wonders if it's going to crack. Let him tell you all about it.
"I had a 7 1/2 ft x 4 1/2 granite island countertop installed the other day and have realized it is not in plane. One edge is sagging about 1/4 inch. I can't really see it with a 4 ft straight edge so its not a really sharp decline but I'm still worried about coming home one day to a big crack running across it.
Is this something I should be worried about? If I could jack that one corner up 1/4 inch it would be perfect. Is there a way to do this safely? If it hasn't cracked yet is it ok?
It has plywood underneath and I believe it is supported evenly.
There isn't really a warranty to anything involved with this so its up to me to fix it. Here are some photos showing the defect."
This is one big piece of granite! Ryan assures me the piece of wood on the top is perfectly straight. Photo credit: Ryan Klak
There is a gap under the piece of wood. Photo credit: Ryan Klak
Here are my answers for Ryan:
Granite is very strong when it's compressed, but when it's subjected to tension, it's weak and can crack.
Tension happens if you push down on the granite and it flexes because of lack of support.
The dip in the granite may be natural from the cutting and polishing process. It's possible for the stone to have a slight curvature.
All you have to do is make sure the island cabinet is solid and that you have SOLID contact between the granite and the island cabinet.
In your case had I known the island cabinet was in the same plane but the granite had the slight bow to it, I might have put some tile thinset on the plywood to fill the tiny voids where the granite doesn't contact the plywood.
If you don't fix this the granite may crack if you have a wild party and someone sits or dances on the granite top. Stranger things have happened at parties.
Right now it would be a HUGE project to reset the granite. If there's a way to inject some epoxy in any gaps you can access, do it.
Do NOT attempt to jack up one corner or edge. That puts enormous tension on the granite and you'll probably crack it for sure.