Concrete elevated floor systems

Elevated concrete floor systems have numerous advantages, which have historically  been underutilized and undervalued in residential construction. The absence of the  inclusion of concrete  floors in residential applications has been due to multiple factors, including the relatively myopic view that residential structures by definition are  to be constructed with wood-frame walls. The advantages of elevated concrete  floors  include the following:

•  Fire is suppressed from  floor to  floor. Concrete  floors easily resolve type II  construction requirements.

•  Acoustics are isolated. Noise transfer from  floors above varies from being  an annoyance to being a significant design issue. A few inches of concrete  can resolve this.
•  They are waterproof.
•  They resolve structural issues of sheer transfer across the diaphragm.
•  In high seismic zones, they can lower construction costs.
•  In high wind threat zones, an elevated concrete  floor increases the lateral  resistance and will increase the durability of a multistory structure, particularly when combined with a concrete roof system.
•  The concrete can be  finished as the  final  floor  finish as desired by stamping  and/or staining, polishing, and sealing, thus eliminating the added cost of  floor  coverings or allowing architectural considerations not otherwise feasible.
•  They can serve as a high thermal mass base material for radiant heat systems distributed by either hot water or hot air.

There are potential disadvantages to be considered:

•  Concrete floors cannot readily be combined with wood-framed walls.  Concrete or structural steel frame wall systems are required
•  Standard weight concrete cannot be supported by wood-frame  floor joists.
•  The cost of an elevated concrete floor has been viewed as being substantially  less costly than conventional wood-frame/TJI joists, etc. (This is not universally the case, requires evaluation on a case-by-case basis, and is breaking  down with the introduction of new alternatives for cast-in-place  floors.)
•  Placing utilities in the  floor system in a multi-story structure can be some- what  more  challenging  than  with  frame  construction,  and  necessitates  design considerations reflecting the nature of the  floor.

1. Cast-in-Place floors
2. Precast floor System