We are doing kitchen upgrade- keeping our cabinets but replacing laminate countertops with granite. Our island is a bit unusual- two 18 " cabinets with a 30" opening between them, so my husband who uses a wheelchair can wheel underneath. We'd like to add 10" to either end of the island, making it a total of 86" long. The width is 36", with the cabinets being 26" and a 10" overhang. We know we need to add extra support for the granite. We are thinking of using two corbels on each end to cover the 10" overhang. Then using the counterbalance brackets I've read about on this forum for the 10" overhang on the long side. My questions are: are 2 of the brackets enough support, or would I need 4 brackets to support the 86" length? And do I need any extra support for the 30" opening between the cabinets? We'd like to get this worked out before the granite guys come to measure and template. Thanks for any suggestions.

Thanks to those who provided specific input :) . Lowes Canada doesn't source the Federal Brace 8-in x 2-in Plain Steel Countertop Support Bracket. Any suggestions for Canadian sources of those? Or equivalent? Trebuchet, I assume I would need three of the Federal Brace 8-in x 2-in brackets? Could I install the plywood inside the cabinets (there is room)? Is there a reason why I wouldn't use the "L" shaped granite support brackets that don't have the cross-brace (knee knocking) like the example below? What about this Ekena Millwork 2"x8"x8" Hamilton Bracket? Price is good. Cold-rolled steel and it's supposed to be appropriate for granite. Is there any way to evaluate the many different brands of cold-rolled steel granite brackets? I am still trying to understand is shimming the bracket end(s) will be required to get a snug fit to the granite, and if so how would that be done? Kudzu, that supplier doesn't ship to Canada unfortunately. This post was edited by feisty68 on Mon, Dec 29, 14 at 13:32

I worry when my 200 lb teenage son puts weight on my 12" overhang ... yours just seems like an accident waiting to happen. I would never think of putting weight on a cantilevered surface like this, but most people don't even give it a thought and some would even hop up and attempt to sit there!

Thank you Joseph Corlett and ABC. I also read about 3 cm slab, when buying quartz we'll make sure it's not below 3 cm. @User I realize now that we should have planned this ahead of the time, but our kitchen vendor is comfortable with the contractor installing heavy duty brackets under the slab, something as per below. I don't know if at this point we should use any other reinforcement. Thank you ! https://www.amazon.com/dp/B0B6GYP1QX?ref_=cm_sw_r_apin_dp_W3QKQEBQJYGF3WZ3P0AX&fbclid=IwAR03q4ekp4IqcWVSWV4uaE4hZffSj25lItaIVh0KlyWXGqSierXFyBJcC3o