Abstract: An expansion and contraction joint assembly for use with installations of tile, slate or marble floors or the like is disclosed. The joint assembly is comprised generally of a base or lower component, a core receiving or upper component, and a cap component. The base component is placed on the floor or concrete slab and the core or upper component is inserted into the base and positioned with its upper end flush with the surface of the floor by the cap. A suitable core material is placed into the upper component to provide a joint assembly which compensates for expansion or contraction of the floor or setting bed thereby eliminating buckling and cracking of the floor.