Strength of Slab Granite countertop with no plywood base


Slab Stone Vanity Installation - I had a company install Giallo Ornamental in my bath. I thought they were going to do a 3cm with a laminated edge on a plywood base. In fact, the owner showed me his shop and the high quality plywood. When the stone arrived at my home it was only 2cm. Apparently there was a big miscommunication error and I know have no plywood base. The granite it installed with two vessel sinks (one hole is cut so that the bowl rests down 3" within the granite and has no support). I worry about the strength of the countertop as one stretch is a diamond shape and is 54" long. Please let me know if it is better to have it ripped up and done the way I expected or to just put decking underneath the slab and within the cabinet. Thank you for your help.


ANSWER - If you ordered 3 cm slab stone and received 2 cm then you didn't get what you paid for and should be reimbursed or have it replaced.  2 cm stone can work fine for a vanity if installed correctly with an apron to make it look thicker if you like that look.

You don't have to have a subtop (plywood base) for a vanity top that is 2 cm or thicker unless the stone is considered fragile (marble class C or less) and is not supported over a long span.  If you do have a subtop then you need to have an apron edge to cover the subtop edge.

The sink can be undermount using an appropriate sealant only if the stone is not fragile and the sink not too heavy.  I prefer to see mechanical attachments.   Good Luck!

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