Thermoplastic building blocks

An architectural molded thermoplastic resin building block comprising a hollow rectangular thermoplastic resin block with flanges and snap-fit interlocking means on said flanges for joining at least two said blocks without the need of an adhesive material, said block comprising two outer opposite essentially flat surfaces separated and joined by peripheral wall segments normal to said two outer opposite essentially flat surfaces, each outer opposite essentially flat surface has four flanges intergrately molded as part of the thermoplastic outer edges of the block such that each flange has an inner and outer surface and is aligned to extend outwardly from each said outer essentially flat surface for at least partially filling a precise amount of space established between a pair of adjacent blocks when at least two of said blocks are positioned as a segment of a wall, said four flanges consisting essentially of two outer and two inner flanges wherein each outer essentially flat surface has two adjacent outer flanges and two adjacent inner flanges, said outer flanges have the interlocking snap-fit means on the inner surface of the flanges facing inwardly from one said outer essentially flat surface and said inner flanges have the interlocking snap-fit means on the outer surface of the flanges facing outwardly from the same said outer essentially flat surface such that the outer flanges with the interlocking means facing inwardly adapted to engage the interlocking means facing outwardly from the inner flanges of an adjacent block for securing and interlocking the adjacent block thereby forming a segment of a wall.