Schedule the installation. The fabricator lays the slab directly on top of cabinets; in general, no plywood underlayment is required. It's held in place with silicone-based construction adhesive, and any seams between slabs are filled with color-matched epoxy resin. Undermount sinks are installed with clips (and sometimes wood braces) that attach to the underside of the countertop. Expect installation for a typical kitchen to take from a few hours to a day.