It depends on the structural support system for your home. An expert can reinforce the joists and add a microtopping. It will be one of the most expensive flooring choices that you can pick. Way more than wood or tile.

Concrete flooring is not a "money saving" floor. It is a life-style floor with a life-style price tag. Add concrete flooring to existing concrete slab is still expensive. The slab concrete is not good enough to make into a "floor". A concrete slab requires shot blasting, micro-topping (high end concrete), colour (if you want) and then sealing (high end epoxy is the best choice).

Add concrete flooring to WOOD JOIST home is even more expensive. As Sophie indicates, the subfloor has to be reinforced to create a rigid surface, then it has layers of microtopping added (high end concrete), colour and sealant (same as above).

In general, these floors cost between $5-$25 per square foot...depending on substrate, preparation, colour/finish, sealant chosen. A "nice" stained/polished concrete floor (with 2-3 colours added to create a specialized effect) can be as expensive as solid hardwood.

If you LOVE concrete...go for it. If you are doing it to "save" on flooring you may want to look at something else. And to add to the joy of concrete, it is often "covered up" by homeowners inside of 3-5 years...because it is, well, as hard as concrete.