We're using tropic brown, which we were told is dense and stronger than some other granite.
We have an island we've made. On two sides, we'll have a 1.5 inch overhang. But on the other 2 sides, we plan to have 8.5 inch overhang. So the top would generally look offset (this design is based on our needs and space).
We were told 9 inches is the max unsupported overhang we can do.
That means that while the 2 sides with the 8.5 inch overhang are OK - at the corner where they meet - if you measure out on the diagonal - it's like 12 inches.
Seems that the only solutions would be to support it somehow, or reduce the depth of one or both of those longer overhangs.
Anyone have any ideas? I thought about fabricating my own solution - getting a flat piece of steel similar to a yardstick, notching the cabinet tops and bolting it down, then having it extend out under the corner.
But the downside is that you'd be able to see it as you sat at a nearby table. And, I don't know if flat steel would even be strong enough. It might need to be a round rod or even have a T in it.
We don't want any corbels/supports per our design. So if I can't figure something out, we'll probably just kill the overhang on one of the edges to solve the issue.
I would suggest a second opinion on the overhang with no support.
I honestly do not have the facts or a definitive answer for you.
I have done many kitchen remodels with granite tops, and breakfast bars.
The last one we did sticks in my mind. Plan was a 16" overhang with corbels.
This number was arrived at, from the granite pieces ordered, that was what was leftover and why waste it.
After all was said and done, moving walls, building 1/2 walls etc ... We realized that with 16" overhang, would not be able to get the huge fridge into the kitchen.
So we backed it off to 12", granite installers were fine with no corbels.
My thought is, you can go farther then 9", exactly how far I do not know.
Sounds like maybe the granite installers are being a bit conservative, they need to guarantee the install.
Maybe others will have a better answer.