Thanks Sophie. I don't like the solutions they have come up with. Adding posts, or stepping out another panel underneath. We found a granite slab that we love and it its all one slab, no seams. That's not the issue. However, I am trying to determine what type of steel supports would work and if the overhang needs to be smaller to avoid the aforementioned options. I assume a stretcher rail would cover any steel so that is the solution I am hoping to find. Apparently the engineer rejected the first plan with steel, but I don't know what the builder presented to him.

Do you need to seat 6?

I think the 36" side hole is so the the two people sharing the corner don't collide quite as much--you should keep that if you can.

Can't you put two posts (or however many you need) running along the midline of the overhang, ~18" in from all sides? They would be far enough under that they wouldn't get kicked or prevent stool tucking. Use a round metal post and powdercoat it creamy to match the cabinets or dark to match counter. The point is to make it disappear or at least not make a statement. You're gonna have stools there. Nobody will see the extra posts. They will offend no one if they are seen.

Have you checked out the "Counterbalance System"? Here are a couple of threads that discuss it from the "Stone Information and Advice (& Checklists)" FAQ (from the "Read Me" thread):

https://www.gardenweb.com/discussions/2516280/kevin-remember-the-6-and-10-rule

https://www.gardenweb.com/discussions/2543583/granite-fabrication-questionswhat-do-you-think

Thanks, we do not need to seat 6. We have a ton of space so it was a nice to have option (so the people on the ends can see the TV)

Posting the proposed solutions would aid in evaluating the skill of your team.

I'm wondering why you need a 43" overhang for counter seating. That's larger than the width of a standard dining table. I would think something half that width would work fine?

Plus how the heck would you even clean the middle of the slab? Most people's arms reach about 30" max.

If it were me, I don't think I'd have more than 18" to 21" for a seating overhang. As CPArtist mentioned, unless you have very long arms, the maximum depth of an island for most people is 60" (30" from each side) -- and to clean that deep an island, most people would have to walk the entire perimeter of the island to reach all areas, including the center.

It is possible you can reach farther, if that's the case, then I would limit the depth to no more than 2x the distance you can easily reach while holding a dish cloth/sponge and performing a wiping motion.

(I can reach 42" if I stretch, but I have very long arms -- longer than others my height (5'10") would normally have. I would also rather not have to walk the perimeter to wipe my peninsula counters, but that's my personal preference -- YMMV.)

But you still need to support the overhang even if it's shallower, so regardless of what you decide do about the depth, you still need to figure out what to do about the support!

Lol. I’m 5’1! I had no idea the overhang was so big until they laid it out. That said, I think I’d want 24” for the side stool (plus the 6” post) so I think that puts me st 63” unless I eliminate the end seating or change the shape.

I think you can get away with 21" on the side seating plus the post. I just measured my stools which are quite wide and they are 18" wide. The 24" clearance given is so people are not elbowing one another.

So 21" + 6" + 25.5" = 52.5"

Cabinets are 24" deep. You need a 1.5" overhang on the working side. So I'm not following how you came up with 63" since if you did 24", that would only equal 55.5".

I'm not sure, but my overhang is 17" and I have a stretcher rail. Joseph said with the stretcher rail, I was fine, but then again, my island is only 84" wide.

They have about a 6” space between the decorative wanescot panel and the cabinet. The side panels cover it, so removing that would require getting new side panels. There is 31” from the cabinet front to the back of the panel....plus whatever overhang we choose.

Install 1" square tube steel or aluminum every 24" from the back of the cabinet fronts, rabbeted into the knee wall, and cantilevering 12" or so for a 15" top overhang. No posts. If your engineer doesn't approve that, fire him.

Thank you, Joseph! I think the issue is that we have a much larger overhang than 15" planned. It is currently spec's for 41" (but is supported on the ends by 6x6 posts.) Of course, I never realized it was so wide. I am fine making it shallower, but was hoping to preserve one seating spot on each end. How do I support the center of the countertop (which would be about 8' between the posts at a depth of somewhere between 30"-41". Does that make sense? I was looking at cantilever brackets, but no one says how far of an overhang can be supported. My dad thought 4" Channel irons could work, but I have no idea.

Post your professionals Ideas. Perhaps they can be modified. As in a complete steel post and railing system that is then clad in wood.

Sophie, they have not come to us with an actual plan yet. Will post it when they do.

You said that you rejected their plans as “too ugly”. Those are the plans I’m talking about. If they technically work and just need to be made aesthetically pleasing, that’s not difficult to do.

The super has informally mentioned some options, but no one has yet presented a solution they think would be appropriate.

With an island top that big, I don’t understand why the designer didn’t do a double-sided island base, using double the cabinets, like these:

Sammy, me too!! Except that we had asked for seats on the end. If it wasn’t feasible, she should have said do.

Here's our 3cm. soapstone supported by 2 large corbels.

The length of the counter there is 108" x 36" at it's widest from the pony wall. Within the soapstone there's steel reinforcement at certain spots. The counter sticks out 11" past the end of the corbel. The height of the counter is 42".