A support block for supporting objects on a roof. The support block is a moulded elastomeric block with a substantially hollow core. The support block can be used as is or in a system whereby a galvanized steel channel is secured to the top wall of the block accommodating the mating of a variety of clamps. In some embodiments, the block is elongate and generally flat and supports a roof mounted object thereon when two or more blocks are supported parallel and spaced apart from one another with the object spanning between the blocks.