Abstract: A levelling apparatus for use between a structural frame member defining a first plane and a supporting member defining a second plane, vertically adjustable between raised and lowered positions, comprising a base section having first and second inclined surfaces, a top section having first and second inclined surfaces, and first and second pairs of half wedge members disposed intermediate the base and top section, the half wedge members having inclined faces mating with the complementary surfaces formed on the base and top section. A threaded rod is disposed longitudinally within the levelling device, passing through the pairs of half wedges members and brackets engaging the back sides of the half wedge members, with nuts threadingly engaging each end of the threaded rod. Rotation of one or both nuts causes longitudinal translation of the half wedge members and resulting vertical adjustment of the levelling device.