Stone Countertop Overhang Support Check

The thickness limit (about 6 in at 2 cm, 10 in at 3 cm) AND one-third of the total depth, whichever is smaller. A 12-in overhang on a 36-in top in 3 cm stone fails the thickness rule and needs 5 brackets 8 in deep - two-thirds of the overhang, so the bracket carries the load instead of pivoting on its tip. Weight from the density you enter, not a lookup. Published limits vary by fabricator; theirs governs.

unsupported limit = MIN(thickness rule: 10 in at 3 cm / 6 in at 2 cm, one-third of total depth); slab psf = density x (thickness_cm x 0.393701)/12; cantilevered weight = psf x overhang/12 per lineal ft; if over the limit, brackets = ceil(run/spacing) + 1 at 2/3 x overhang deep.

Stone-industry countertop support guidance, named as GUIDANCE and not a code section; published limits vary between fabricators and stone types.

Fabricator and stone-industry support guidelines are published freely; several independent references state the thickness pair and the one-third rule together.

Estimate. AHJ and licensed professional govern.

Field names used by the API: overhang_in, total_depth_in, thickness_cm, run_length_ft, bracket_spacing_in, density_pcf, thickness_limit_in, one_third_limit_in, governing_limit_in, psf, overhang_weight_plf, overhang_weight_lb, brackets, bracket_depth_in

• Two rules, min governs thickness limit and one-third-of-depth limit are both checked; the smaller controlsstone-industry support guidance (stated together across references)
• Limits vary the thickness pair is overridable and bracket spacing is an input because published figures differ by fabricatorconflicting published fabricator guidelines
• Density entered no stone-density table is shipped; 170 pcf granite is a default, not a claim about a specific slabuser input