The fabricator's plywood subtop viewpoint seems to me to be valid only if cabinet wood is significantly stiffer than the plywood. Otherwise, their argument would apply equally well to the supporting cabinets themselves. Exterior plywood has pretty stiff resin between layers, so its flexibility where weighted by the granite should be low. On the other hand, how well plywood would support an overhang is questionable. It would seem to me that a box channel beam with section height large enough to provide good stiffness would be large enough to weaken the granite if a slot that deep were to be cut into the granite to hold it. A shallow slot for locating the beam would be ok, but all beams and slots must be precise so support is equalized. If, as implied by cloud_swift's photos above, the plywood is mainly a means of retention of the beams, which do all the supporting, then the fabricator's plywood flexibility argument is seriously, er, weakened. I would imagine that the following would work as a conceptual approach. Adhere beams to the granite as required for support. Adhere plywood or other wood in between the beams that is barely lower in height. Use the wood as the point of attachment for whatever covering trim is desired. For a bar overhang without using typical corbels, I think I could use polished or brushed stainless steel beams (thickness TBD) set into the supporting half-wall framing. A scheme to keep the lifting ends tied down and of uniform height would be needed, as would a means to equalize the pivot side heights and keep the beams from compressing the wood there. More simply constructed, if flatness is ensured, is the steel plate method used by sherilynn shown near the top of this thread. I might opt for a thicker piece, depending on some analysis. Other approaches could be equally valid. kas

I had exactly the same problem happen about three months ago. Bought 6 slabs of White Princess (a white quartzite) that were to have a 3cm square edge. Upon delivery to my fabricator who is very well known and reliable in my area, he rejected all of the slabs. The driver called me (on the golf course) and I had a "four-alarm fire" on my hands running around, calling everyone, including my GC, and everyone was in a HUGE huff. Essentially the fabricaotr felt that the slabs were too "delicate" to rod and that the color was too light and might have the same problem that you specified. After numerous discussions all around we came to the mutually agreed upon conclusion that the best way to deal with this was to have double thick plywood over the counters, NOT rods and the overall height of the counter would thus be 37.5". The island overhang would thus also be doubly-supported and the granite would have enough support below it to be fairly stable. I then had to go back to the counter people after that and confirm that the extra height was not a problem--while they said everything was fine, I never found out if they had to change anything--they talked to my GC. HOWEVER, my fabricator did tell me that he was still a wee bit worried about my slabs and that they would be treating them extra carefully....not actually what I would hope for as I was hoping that my granite would be nice and tough, not fragile and high-maintenance! Still, I love the material and I can't wait for them to fabricate at the end of this month when my cabinets are done :) Good Luck!!

cawfee, I've seen large tables made of 2cm granite, without any plywood. (!) They've never cracked. I've seen many renovators who overkill things, just to be sure. Most do. In fact, they all do. Otherwise things would crack or move later. How many simultaneous dancing 200-pounders do you want to support on your countertop, this is the question. I've seen kitchens that were more solid than the walls and the house. How many future earthquakes and foundation cracks will your house live through before your countertop also cracks, this is the question. At some point you have to let go of the wish to overkill, and call it good enough. This is up to you. Sooner is usually the best time. Otherwise you go crazy trying to do ever better. So, "... Obviously, this needs supports ..." is true, to an extent, but what to do next is up to you , and up to your sense of overkill -- Part 2. "... seen mention of 2x1 rectangular steel pipe as supports (12-16 inches apart)..." Search on the term box girder to reassure yourself about "... rectangular steel pipe..." It's the strongest. For its size. But, this following statement isn't knowledge: "... I know I need to support at least 12 inches of the overhang (13-14 to be safe)..." It's a judgement call or a hunch, like most other rules of thumb. You choose "... plywood sit on top of these metal pipes or are the pipes routed into the plywood..." You choose because it doesn't matter. "... screwed down to the cabinets or is the weight of the slab sufficient to hold them in place..." golly, is the weight of the slab a lot of weight? do you want to drill a hole and screw it down just for greater overkill? -- Here it appears you want to save 0.75": " ... lower profile of the 2x1 over the 1 3/4 ..." I'm not sure what you are referring to. I read a lot. I remember a lot. If I don't know what you are referring to, I'll bet that the other readers also don't. I'll bet that most pro installers don't. I think you need to be more diligent about your descriptions. For your slab, nobody knows " ... how much deflection can granite handle ..." Therefore, nobody knows "... What wall thickness ..." But, in my estimation, there is nothing wrong with getting heavyweight wall thickness tube ("square pipe") since overkill is the objective. But, not much is lost if you get lightweight wall thickness tube. All you lose is a bit of the excess overkill. In Engineering, it's called a margin of safety. But it's the same thing. If you are willing to crack a few slabs under very tightly controlled conditions you will know factually how much weight cracks them (and how much microdeflection they will take). It's just a stone from a quarry. It's not a processed material from a factory made and "scientifically studied" material with "known" properties. Don't ask for answers that won't be good numbers. Anyone can invent a numerical answer for you if keep insisting on having numerical answers. How much overkill is enough? Hard to tell, not seeing anything from my keyboard here. Do you know anything about the flex in your floor? This is a big thing. This is the one thing that I recommend you to go look into before proceeding.

The difference with quartz is that the manufacturer warranty it and installers are certified by that manufacturer and must use their specifications and requirements so the warranty is good. They won't give you the same leeway to come up with unique solutions sometimes. I would contact Zodiac and find out what requirements they give their installers for that size and type of overhang and then work from there. You can probably find a telephone number or email on their website. Sue