If you are a foundation contractor, one way to secure more work in this down economy, and into the future, is to do more work on the contracts you have. Your men are on the job, your equipment is there, the concrete pump is there—but you only cast the foundation walls and footings. Some of you have made the jump to abovegrade concrete housing and most of you have at least contemplated it.

If you aren't quite ready to jump in with both feet, why not go part way—cast the deck (the main floor of the house) in concrete. You might not be able to increase the number of your projects this year but you can increase your gross sales. One contractor who has built several decks said concrete decks cost around 30% more than a traditional wood deck. So why would an owner spend more to get a deck and what is in it for you?

There are many good reasons for owners to consider concrete decks.

• Safe room. Clients get the ultimate safe room—a basement with 6 to 8 inches of concrete on three or four sides and 6 to 8 inches above. A room with those specifications can resist just about anything Mother Nature can throw at it.
• Noise reduction. Concrete floors are quiet. Six inches of concrete has tremendous sound absorptive qualities at all spectrums of the audible scale.
• Fire protection. A fire that starts in the basement (say, the furnace room) will take much longer to spread and can easily be contained if there is a horizontal concrete layer separating the fire from the balance of the habitable space.
• The elimination of mold and varmint damage. Mold needs three things to grow: mold spores, moisture, and a food source. Concrete is not a food source for mold growth like wood or drywall, so this is not a concern. As for wood eaters such as termites, mice, and carpenter ants—if you find one that eats concrete then we've got much bigger problems to worry about.
• Thinner floors. A 6-inch concrete deck can span up to 20 feet without intermediate support. It would take at least a premium grade (Douglas Fir-Larch #1) 2x10 spaced 12 inches o.c. to span that distance—and wood won't provide any of the other qualities discussed. The continuous connection between a concrete deck and a standard 8-inch foundation wall produces a strong structural detail at the wall/ floor juncture, improving the structural efficiency and performance of the floor system.
• Radiant floor heating. In-floor heating is the ultimate in comfort and efficiency. Concrete floor systems are the best material to use with radiant heating systems.
• Decorative concrete floors. Stains, stamps, diamond polishing, and a host of other concrete finishes will add durability, beauty, and functionality to your home.
• Energy efficiency. The most efficient method of casting foundation walls and decks is in a single-placement operation. The resulting monolithic cast will provide the most airtight, structurally integral basement wall/ deck available on the market with little, if any, material waste.

With standard forming systems, adding a ledger form to the system enables you to join vertical forms to horizontal. Photo: Wall-Ties and Forms

What's in it for you, the contractor, in addition to more work and money from the same project?

• Top restraint. You will get the best support possible for the top of the wall so there won't be any more callbacks because an excavator pushed in a wall during the backfilling operation.
• Anchorage to deck. You won't have to be concerned about anchor bolts giving way during backfilling.
• End wall bracing. There won't be any more issues about the possible lack of “required” bracing for the joists parallel to the end walls.
• Performance. There are fewer problems with cracks because the top of the wall is not only fixed, it gives greater load capacity to the wall itself.
• Floor diaphragm. If you are building walkout basements, there is always concern because there is no soil opposite the backfilled wall to resist the force of the soil. With a concrete deck, you have the ultimate diaphragm, which can transfer load to the transverse or perpendicular walls.

The ACI 332, Residential Concrete Work Committee is contemplating the inclusion of decks in future versions of the standard. Empirical tables will likely be part of the output of the committee reducing or eliminating the need for an engineer on many decks, or if an engineer's approval is required, the cost can be substantially reduced.

What do you need to begin pouring decks as well as walls? Fortunately, the form manufacturers have anticipated this need and have all of the accessories and tools required to form, brace, and support the decks. Decks typically are cast at the same time as the walls, which makes casting a one-step operation. The two major needs are a ledge or support to form the transition from the wall to the deck and to support the deck form. The second is the temporary intermediate beam and shoring system to support deck form panels.

How does it change your operation? You will spend more time on the job (therefore more compensation) and you will develop crews who can be as efficient with wall/deck combinations as they are with wall/footings (relative to cost or man-hours).

Ready to place concrete; forms and reinforcement are in place. Photo: Van Smith, Wallkill, N.Y.

One aspect of building concrete decks that is more important, compared to building with wood, is planning. With wood, you simply drill and cut openings where required for plumbing chases and vents. Wiring is installed after the wood deck is already in place.

Although it is possible to drill and saw concrete after placement, it makes more sense to use blockouts and simply eliminate the concrete from locations where stairs, ducts, and chases are required. The location and size of these elements should be included in the plans. Doing this saves time and cost. This planning also helps engineers know where additional reinforcement may be required at the openings.

Wiring can be installed in surface mounted “Wiremold” or similar products, but it is more efficient and aesthetically pleasing to have conduit in the slab instead. The location of lights, outlets, and switches can be easily predetermined. When in doubt, install an extra conduit. Depending on your local codes, the concrete contractor may be able to install the conduit with a licensed electrician making all of the connections.