Countertop overhang support — the seated cantilever limit and when a bracket is required
A seated overhang has a hard unsupported limit: ~6″ at 2 cm, ~10″ at 3 cm (NSI). Go past it and the stone cracks at the cabinet line — a deeper seating overhang needs a corbel or hidden steel bracket. A standard front overhang is only ~1¼″, so it never needs support.
What this diagram shows
A side cross-section through a kitchen island comparing two seated overhangs. On the left, a 15-inch seated overhang with nothing supporting it cracks at the root where the slab passes the cabinet, because unsupported stone can only cantilever about 6 inches at 2 centimeters thickness or 10 inches at 3 centimeters per Natural Stone Institute guidance. On the right, the same 15-inch overhang is carried by a corbel or a hidden steel bracket and is safe. A standard non-seating front overhang is only about 1.25 inches, well within the limit.
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