I need help with a question. Any one doing 2cm with build up edge here that can help. I have a customer that is asking about an overhang around 12" off cabinet. I think they will need brackets to help hold this up. But as always the info you need it not to be found. I will be doing a 4cm edge with a floating deck underside of the countertop. What do others do in this rather normal situation? I have been looking online for an answer but can't get a response from Silestone nor find any info regarding this material. It's rather new and maybe the same as 2cm anything else (Silestone, Granite, etc) that produced. So if you have some other material 2cm that may have guidelines then please let me know what they state. I always have thought 1/3 2/3 rule. 1/3 as overhang and 2/3 as cabinet or knee wall or what have you. Any ways this is a shot maybe one of you may have an idea.

We have put corbels on larger overhangs before. they help support the top and don't look bad. you can also run some support plywood attached to the corbel the length of the top and silicone the plywood to the top. the plywood will be hidden by the drop down edge, so all you will see is the corbels. It's a thought anyway. good luck.

I think with a 12" overhang, I would use a corbel or at minimum a subtop. You could always do the counter with a subtop only and then put a bracket later if need be.

With ES we use 1/3 2/3 . If the tops overhangs by 1/2 of the amount it is on the cabinets your ok. That being said, if the customer has kids that will be climbing on the counter I would suggest a corbel or steel support. If it's two adults you should be fine with a 12" overhang on a 36" deep top, with no additional support except the sub deck.

Do any of you guys worry about the build up adhesive letting go? Obviously, if it is sitting on the cabs with the standard overhang, no problem. The 12" overhang?

If I was still selling Silestone here is what I would tell the fabricator on this question.  Use a solid substrate and support with Corbels evenly spaced at no greater than 36-inch intervals.  Overhangs over 18 inches need to have a solid substrate along with a leg or column for support.
Paul

Ed, You can span the 12" with no additional support. Just make sure you use solid substrate(mdf). If you span anymore than 12" then you will need additional supports. If spanning 12" on a 1/2 wall and it is a straight run then obviously the peace is not going to want to sit there on its own and you then will need to add additional supports.

Had similar challenge; I simply inserted angle iron rebated into the mdf @ 350mm centres and achieved 450 overhang no problem, albeit I had 50mm downturn.

The angle must be screwed to the mdf & helps if mastic is used to adhere together.