Abstract: A unitary paving block having an exposed surface in use having a multitude of markings to simulate individual, random paving elements has a periphery with a shape which enables the block to be laid with other similar blocks in an irregular, substantially unrepeated paving array. The shape of the periphery of the blocks is such that the blocks can be laid with each block angularly moved with respect to each other and/or laid in staggered relationship with respect to each other.

Abstract: A composite roofing element comprises a first layer of aggregate based material, a second layer of material having a density less than that of the first layer and has a wedge shaped region depending from its underside. The wedge shaped region is preferably integral with the second layer which can be made of an expanded polymer, expanded polystyrene being particularly suitable. Overlapping structure on the side edges and a recess in the thick end of the wedge enable adjacent elements to interlock with each other. By using such lightweight roofing elements the requirement for a substantial load bearing supporting structure is reduced.

Abstract: A lightweight concrete product in the form of a concrete roof tile is made from a cementitious mixture comprising a porous lightweight aggregate, an hydraulic cement, water, an agent for enhancing, flexural strength and an agent for enhancing the water retention capacity of the lightweight aggregate, the proportions being such that the product has satisfactory impact and flexural strengths.

Abstract: An interlocking roof tile which can be made by extrusion, pressing or moulding has an upper edge; a lower edge which is visible in use when the tile is laid in overlapping relationship with at least one tile of a next adjacent line of the tiles; an upper surface; a lower surface; a supporting understructure; two oppositely facing side edges; an underlock extending along one of the side edges and an overlock extending along the other of the side edges, the underlock having a lower end and an under surface which forms part of the under surface of the tile, and a lower edge portion having an under surface which includes a part of the under surface of the underlock, and which overlaps, in use, at least one tile of the next adjacent line of the tiles, characterized in that the upper surface of the tile extends continuously from the lower edge to the upper edge, in that the upper and lower surfaces are cambered from the lower edge to the upper edge and are substantially flat when considered in cross-section taken a

Abstract: An interlocking roof tile (1) of which the leading end portion (12) at least as far as the lower end of, and including the underlock (6) is tapered in the direction of the leading edge (5) of the tile (1).

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..