575 South is a new mixed-use luxury condominium building located in King of Prussia, PA. This 4-story building utilizes 88,593-square-feet of Hambro Structural Floors bearing on steel studs. Developer Toll Brothers chose Hambro composite floor joists for its superior fire & sound ratings. Hambro has U.L. Fire Ratings for 1, 2 and 3 hours, with no need for fire dampers, and an STC 57, one of the highest in the industry.