Exterior Design For 3 Story House . The home was designed for thermal efficiency and to maximize flexibility of space. Most concrete block (cmu) homes have 2 x 4 or 2 x 6 exterior walls on the 2nd. Spacious ThreeStory Cube House by Canvas Homes in Canada from www.stuffmirror.com Bend the rules with your exterior. The best 3 story house floor plans. See more ideas about house design, 3 storey house design, house.