Abstract: A screened enclosure having aluminum structural members, joints interconnecting the structural members, and screen panels formed by the interconnected structural members. The structural members include two-piece box beams formed by two mating extrusions, wherein flanges of the extrusions continuously engage each other along their length by means of interlocking lips, and one-piece hybrid beams. The joints include rigid joints and hinged joints, wherein the hinged joints allow at least one degree of freedom between the interconnected structural members. A computer-implemented design method determines the reaction loads on the individual structural members and determines compliance with applicable building construction standards.