Thickness is dependent on the overall size and use of the paver. If the paver is 12", 18" or 24" square they can be manufactured at 1 3/4" thick. If the unit is 30" square, minimum thickness is 2" – and if it is 36" square, minimum thickness would be 2 1/4" thick. These minimum thicknesses are only correct, however, when the pavers are solidly set in mortar, thinset or bituminous, or used vertically. If set on a loose system, such as sand set on pedestals, minimum thickness would increase by 1/4".