More and more of the nation's leading architects and contractors are today engaged in an all-out search for materials and methods with which to achieve economy in building. Out of this search a definite trend has developed toward lightweight floor construction as one of the most effective ways to keep costs down and at the same time improve the quality of the structure. One of the more successful materials being used in lightweight floors is perlite concrete fill. Applied over various types of light structural forms in clouding corrugated and ribbed steel, cellular steel floor units, ribbed metal lath and paper-backed wire mesh, lightweight perlite concrete fill results in a dead load considerably less than the rated live load. Ready mixed concrete is very definitely in the perlite picture. When transit mixing perlite concrete for the fist time, it is suggested that the perlite manufacturer be consulted for suggestions as to the correct mixing time and procedure. These may vary with the type and age of locally available equipment. The mixing procedure used by many transit mix operations is as follows: determine the load, based on the mixer ration as shown on the name plate; add to the mixer the correct amount of water for the load, leaving out about 30 gallons; the correct amount of air entrainment agent and cement added to the mixer and mixed until a slurry is formed; add the correct number of bags of perlite concrete aggregate; upon arriving at job, mix at top speed for not less than 5 or more than 30 minutes. Wire fabric reinforcement is recommended for all types of perlite concrete floor fills except where wire fabric is incorporated as part of the forming material. The recommended method of finishing perlite concrete is steel troweling which produces a smooth hard finish to receive a final floor covering.