Abstract: A ballast block is disclosed in the form of a planar plate member. The plate member has a top and bottom surface, front and rear end portions and oppositely disposed lateral edges. The end portions include a mechanism for preventing substantial uplift and rotational displacement of the block when its end portions are interlinked in overlapping relationship with the corresponding end portions of like ballast blocks.

Abstract: A roof tile is provided with a pair of batten lugs and a pair of stacking lugs protruding from the bottom side thereof. The batten lugs are positioned very close to and taper to the edge at the head end of the tile so that the thickness of the tail end of the tile may be relatively thin and may be equal to the thickness at the edge of the tile head end. The stacking lugs are positioned longitudinally away from the tail end of the tile so as not to interfere with tile overlapping. The thickness of the tile from the front surface thereof to the tip of each batten lug is substantially equal to the thickness of the tile from the front surface thereof to the tip of each stacking lug such that the tile may be stacked with other similar tiles without need to rotate every other tile by 180.degree..