A full substrate underlay must be utilized under the material for added strength. Use exterior glue plywood or cement backer board as the underlay material.For all 3cm Granite structures:
Spans should not exceed 24" between support centers. Spans should always be kept to a minimum to prevent deflection of the stone.
Maximum length is 118" for sections without cutouts.
Maximum length is 100" for sections with cutouts.
For structures with support on 3 sides (e.g., dishwashers, desks, and frame-less cabinets) follow the 24" support criteria above, however, adding support to strengthen the unsupported side is recommended. Consideration should be given to the type of stone being used (fragility) and the intended use (load bearing) when assessing support needs.Overhangs for 2cm Granite that exceed 6 inches will require additional support structures
For an overhang more than 6" use a proper support system such as solid substrates, legs, brackets, corbels, or columns.Overhangs for 3 cm Granite that exceed 10 inches will require additional support structures:
For an overhang more than 10" use a proper support system such as solid substrates, legs, brackets, corbels, or columns.Half wall (knee wall, pony wall) overhang support requirements for both 2cm and 3cm granite:
For overhangs less than 1/3 the depth of the top [i.e., support wall is 4 inches, countertop is 6 inches, overhang is 2 inches] no additional support required.
For all other half-wall overhangs, corbels are required to support the overhang where the bracket depth is 3/4 of the overhang depth. Spacing for corbels is a maximum of 24 inches throughout the span.
Acceptable support materials are MDF board, plywood, structural steel, and wood. Particleboard is not an acceptable support material.