I am finishing a bathroom counter.
It's approx 75"x25" and will have two sink bowls

Right now I have the top made from 3/4" plywood. It is not marine grade
plywood BTW. The tiles are cut and ready to lay.
My original plan was to use structural adhesive to attach the tiles
to the plywood and then grout.
But I bet I need a waterproof substrate - backer board, cement
board, Hardiboard? Problem is I don't want to make the top any thicker
than it already is, though 1/8" or so would be fine.
Any suggestions welcome on materials and method. I only want to do
this once.

Thanks

Rex B
DFW

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I can see 2012 from my front porch