Precast prestressed concrete enjoys wide use in all types of residential structures; particularly multiple units where the repetitive use of standard components manufactured in a factory can be fully utilized. The significant benefits of superior fire resistance, sound control, durability and low maintenance, owners and designers alike recognize rapid construction and attractive exterior treatments. The most common floor and roof elements employed are 205 mm deep untopped hollowcore units. These slabs can span up to 9 m or more without intermediate supports. Longer spans can be achieved by using 254 mm or 305 mm deep hollowcore units. For hotels, motels and apartments the hollowcore slabs are oriented to either span between load bearing shear walls or to span from the central corridor to an exterior wall. Slabs can be cantilevered up to 1.8 m to form exterior balconies. Bearing walls may be of masonry, precast concrete or cast-in-place construction. The use of precast walls speeds the erection process. Construction rates of 1 floors per week and better are often achieved. Architectural insulated panels for the exterior of a building can provide a durable, attractive, energy efficient envelope. Ancillary recreation, parking and convention facilities are commonly constructed using precast concrete framing with long span roof and floor members.