The thickness of the stone slabs used in a given project shall not vary by more than 1/8″ (3 mm) between the thickest and thinnest slabs.
Exposed edges of adjacent stone slabs must be matched in thickness and properly installed so that neither the top nor bottom surface exceeds lippage tolerances.
Joints at Materials Transition.
Visible joints between stone and other materials (e.g., cabinetry, gypsum wall board) shall be 1/8″, with a tolerance of ±1/16″ (±1.5mm), and filled with a soft, elastic material. Exceptions to this would be the joint between a full height backsplash and the underside of the upper cabinets, which is to be a nominal ¼” with a tolerance of ±1/8″ (±3 mm). Concealed joints between the stone and other construction materials (e.g., stone-to-wall joint underneath the backsplash) shall be sized to ensure a minimum of 1/8″ (3 mm) of cover.
Slab Flatness and Levelness.
Individual stone slabs are to be flat within 1/16″ (1.5mm) when measured with a 4′-0″ (1.2 m) straight edge. Finished countertop surfaces including multiple stones are to be both flat and level to 1/8″ (3 mm) across 10′- 0″ (3 m).
Seam Filler Materials.
Seams in the stone countertop are usually filled to the level of the top surface. The most common filler materials are polyester resin, epoxy resin, elastomeric sealant, and grout. Elastomeric sealants can be made from silicon, polyurethane, or acrylic bases.