https://www.houzz.com/discussions/2966150/help-me-finalize-island-placement-aisles-island-overhang#n=16

A great resource but mixed reviews of the 12" overhang...

I been reading on this they say 12” for barstool height counters, 15” for standard counter height and 18” for dining table height. The taller your chair/stool the less knee space and vice-versa

15" overhang for counter height seating, especially if it's going to be used for dining. We aren't tall (5'5", 5'9") and debated this topic as well, and ultimately decided it's just better to have the comfort space than to risk anyone feeling cramped.
It's your home-- take the extra couple of inches and be comfortable!

Also, try going to a furniture store to find counter height seating to try out. You might need to create a false barrier under a counter height dining table at the 15" depth (using a saddle stool or something) to simulate cabinetry, but it'll be better than nothing!

The minimum recommended overhang for counter height seating is 15". Your GC is wrong.

@T B thanks! Do you have extra space for the knees with your 15" or hit the cabinet?

Put yourself in a chair at a comfortable location relative to a tabletop. Take a tape measure and measure how far under the table your knees extend. You will find it is comfortably less than 12". whatever overhang you decide make sure it is properly supported.

15” is the NKBA minimum for a 36” H counter. The contractor, who is also evidently acting as the designer too since he is giving bad design advice, doesn’t want to have to do the engineering and planning for support that a 15” overhang will need. It will need planning skills that he lacks.

You have to to create a load path that minimizes the deflection, and carries the weight of the counter down through appropriately robust cabinets, to the floor/subfloor. Those cabinets have to be correctly attached to the floor/subfloor as well. Steel will often need to be used. It’s always a custom design response.

We used 1/4” steel here, with a minimally welded flange to decrease its deflection, and then a center post to be able to have seating around all sides. The steel has tab bends that bolt to the cabinet’s reinforced side, and over which the decorative door panel was installed. The cabinet notches to accept the steel were planned before the panel was finished, so there is no raw wood anywhere. The island has fully attached blocking under the toe kick area, to which the reinforced cabinet floor attaches, so no tipping risk because of the narrowness. All this was accomplished during the cabinet design phase, before any cabinet building began. Overhang support has to be integral to the cabinet design and build. A different island design would have a different solution.

Island Style · More Info

I think the NKBA guidelines are 15” overhang for counter height seating. We only have 12” due to space limitations and it’s totally fine, but adults don’t eat at my island. We typically just use it for perching while keeping the cook company, or kids eat breakfast there. If I’d had room for 15” I would have done it.

We have an 18” overhang on the portion of the island that is at dining table height. 15” at counter height sounds right; I am not a pro by any means but 12” just doesn’t seem enough.

N...we have a peninsula with a 15-inch overhang. I'm 5'10" and my knees just brush the back of the peninsula cabinets. However, I do have long legs. Ditto for my 6' DD. Both my 6'7" DS and 6'5" DH have to "straddle" the peninsula b/c their legs don't fit.

In retrospect, I wish we had done at least 18". My DS never sits there b/c it's too uncomfortable and my DH will occasionally sit for very short periods of time. Our seating isn't used that much anymore since my DD is away at college most of the year and I prefer table height seating. It does get used more at Christmas when we're decorating Christmas cookies as no one minds the discomfort while decorating!

If you're going to "try it out", sit at the counter you're testing for more than a few short minutes. You need to sit for more like 20 to 30 minutes to get a true feel (usually not practical in a store, but maybe take your tablet/laptop and work on it there to help pass the time).

One last tip our hardware salesperson gave us: for the storage cabinets you mentioned under the overhang, consider using flat cabinet pulls that attach to the top of the doors. They disappear under the overhang and will keep knees from knocking painfully into traditional knobs/pulls when seated.

At least 15 inches if you plan to eat there--food drops on your lap when it's only 12 inches! Need to be bellying-up to the counter to keep the mess down.

15"

you can use this type of support.

https://www.google.com/search?q=steel+countertop+supports&client=firefox-b-1-d&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi42prxuJLlAhWHiOAKHVKPCZcQ_AUIEigC&biw=1536&bih=713

Thanks! We will definetly have a support bracket. Appreciate your comments.

I’m tall and we have 12” and it is fine. But IMO it depends on how you use the counter if it is for eating all your meals than a bit more would probably be better but if just a perch for a visit or a quick bite 12” is just fine. I have not read any actual rules that state 15” so do waht works for you as for support both need it and should be installed along with the cabinets as steel supports under the counter no corbels needed.

How can someone who supposedly does kitchen design NOT be familiar with the 31 Rules of Kitchen Design? Even if you are Canadian. These still apply, and are very well known.

Rule #9