A roof top structure support has a flat bottom rigid base to be positioned on a roof and spread the load supported by the support substantially evenly over the surface of the base in contact with the roof. A tower rises from the base and includes a slot across the top thereof and a bore therein extending downwardly from the bottom of the slot and adapted to receive a threaded rod therein. The slot in the top of the tower is sized to receive a strut therein. A bolt extending through the strut and into the bore secures the strut to the support. Struts and other structures can be supported above the tower and slot by threaded rod such as “all thread” screwed into and extending from the bore.