By support, do you mean the corbels? They would be more decorative than functional. Assuming that the entire top is 2" maple butcher block, a 13" overhang would not require any support, IMHO.

Hi there- I'm not sure my information comparing marble to wood will help, and on top of that, I'm confused about this issue too. My original KD insisted that I needed legs or corbels for any standard overhang. The KD I ultimately went with said you can always have a 12" standard overhand without needing any supports. I'm assuming that your butcher block will weigh a bit less than a stone would so perhaps you'll be fine without the corbels. I can't wait to see your finished kitchen...do you know how many times I run across something in that buttery yellow color and think "that would look so good in her kitchen....."

OK, you both misunderstood so I must have explained wrong. Our overhang is 14". In addition to the corbels, if you look at the 1st picture, there is a 13" solid overhang (skirt?) UNDER the butcher block and on TOP of the corbels.

So, the corbels are actually touching this 13" skirt.

Hi 2LittleFishies,
I don't know if you need the skirt structurally (you probably do is my guess).
But I do think it adds a lot in a good way aesthetically.
It helps tie in the overhang to the rest of the island
and adds some "weight" to the whole design.

I know fabricators sometimes use metal strips to brace overhangs. They are basically invisible and very strong. I think sometimes (maybe always?) they are inset into the granite. I would want to do that and then use some lighter, more graceful corbels on the corners. I believe the corbels would serve an aesthetic purpose more than a functional one.

I agree that almost 4'' thick top is way too much.

I think the skirt is 3" and the butcher block is 2".

If you need support, I would consider a metal bracket like what was mentioned above. Considering you island is already below standard height, I would not want a 3" tall skirt taking up even more leg room. We used these and you can't see them at all.

Here is a link that might be useful: Freedom Bracket

malhgold-
Do you put a wood bracket over those, or no?

Here's a pic of my island. There aren't any wood brackets, but I do have the posts at either end. That was a design feature though and didn't "need" them to hold up the island. I think on the website they tell you how many brackets you need, what size and how far apart they should be based on the overhang and slab size.

I have the Freedom Brace with my 13 1/2" soapstone overhang. We have no corbels, posts, or aprons.

How do you know what size bracket you need?