Concrete slab for basement floor

[Gary KW4Z]

In a home I'm building I am planning to use "Superior Walls" which say they set directly on compacted stone rather than concrete footers. You then come in with the concrete for the basement slab. What I would like to achieve is a concrete look (finished that is) like the floor you see in Lowes with a sheen on it, totally smooth. I also certainly don't want to experience cracking in a basement slab either so consider this a two part question.

What are the techniques I need to specify to obtain this smooth finish like the floors in Lowes or Home Depot?

What is the best steps to take to achieve a basement slab that will not crack as easily as I may just keep the bare concrete as the floor rather than put carpet or some finished floor on top of it? At this point the home's width will be span by the Floor Trusses so there most likely will not be any load bearing down on the slab, in the middle, except stick framing walls we put up but none are expected to be load bearing walls.

Thanks in advance for your answers

[Chuck]

If it was me I would provide minimum footers with those walls even though they say that non are required. Use 8 inch deep and 12 inch wide with (2) #4 rebars running continuous along the length of wall. For the slab if you want to be conservative use a 5 inch deep slab on grade with #4 rebars each way at mid depth at 18 inches on center. This would be better than using welded wire fabric. Fabric mostly gets stepped on and winds up close to the soil. Be sure that you provide a 4 inch gravel base with vapor barrier on top of the gravel base prior to pouring the slab.

Good luck.

CID...

[Josh]

With Superior Walls, it is absolutely mandatory that a crushed rock footing be used; the "system" requires them. There are specific requirements for the width and depth of the footings to provide the necessary load bearing capabilities. Substituting with concrete footers, even though they can support the load, will void the Superior Walls warranty against water infiltration and will probably result in your building inspector failing you.

As far as the slab goes, ditto what Chuck said. If you want a glass smooth finish, you'll need a good concrete guy with a power trowel. After they screed and hand-float the concrete, which is where most slabs would be considered done, they go over it with the power trowel, which is essentially like a big floor buffer. They continue to do this as the concrete sets, pushing the larger aggregate down into mixture, and when done properly the result is a floor like at Lowes or better. You can even rent one and do it yourself, but your results may vary.

The other thing that will help to prevent the floor from cracking is to use fiberglass reinforced concrete. This will typically cost you $5 to $10 more per yard of concrete, and it's usually done in place of the rebar, but doing both would give you a very strong slab. What I don't know is if you can still get a glass smooth finish with the stuff.

[Yo Yo Yo]

While not a professional, I have used add-in mesh. It seems to work okay save for the surface. Don't get me wrong - I think it's a great idea, but getting a smooth surface with it is difficult at best.

-Alex