Concrete slabs are common foundation/floor systems in many parts of the world, particularly in warmer climates with soils that are stable (i.e. not expansive or otherwise active).
Typically, building a concrete slab consists of (from the ground up) 4" of sand, gravel, or crushed stone; a layer of 6 mil polyethylene used as a vapor barrier (seams to be overlapped a minimum of 6"); a layer of wire mesh - usually #10 wire welded in 6" squares (6x6-10/10) which is embedded in the concrete; and 4" of 3000 psi concrete. The edge of the slab is insulated, typically with a rigid foam product.
Michael with
Floors 2 U prefers slab construction, because it can be less expensive than other systems. Also, with a slab, you never have to worry about a squeaky floor!
Slabs are pretty ridgid structures. They don't have any "give" like a wood floor has. For that reason, people with back problems have often attributed increased aggrivation to standing on concrete floors.
Most of the literature suggests that this problem occurs when people are forced to stand on concrete floors for extended periods - as in an eight hour shift at a factory.
These problems are usually relieved with the addition of a cushioned rubber or "ergonomic" pad. If your home is carpeted, and you don't plan to stand directly on the exposed concrete for hours on end, you shouldn't have any problem with a concrete floor slab.
Slab HeatingSome think that a floor slab is cold. Studies have shown that most of the heat loss in a slab is through the edge. The edge of the slab can be insulated to reduce the heat loss through the slab into the ground.
Anyway, a cool floor may be just what you want if you're building in Florida!
In addition, you may choose to heat your new home with a radient heating system, embedding the heating coils in the slab. This scheme insures a warn floor in winter.
Slabs are either designed to be monolithic (turned down) or poured within a typical (concrete or masonry) foundation.
Don't know which type you should you consider? First look at some local construction in the area where you plan to build. See what others are doing. Chances are there are good reasons for what is typical in your area. These reasons may include climate and soils prevalent in the area. Also talk to your local building official. He'll tell you what the local requirements are.
There may also be site conditions which dictate which type of slab is best for your lot. A flat lot could lend itself to a monolithic slab, while a lot with significant slope would favor one with a foundation wall. A very high water table on your lot may dictate a post tensioned slab that "floats" on the lot.
Radon
Speaking of soil conditions, if your area tests high for radon, take a look here for design techniques to reduce the radon threat with slab construction.
Your slab will also have to be set up to accommodate the structure that will rise above it. You'll have to tie the wood framing to the slab to keep it from blowing away, and you'll have to take care of plumbing supplies (water) and waste.
