Dont Know Remodeling

Many basements are constructed of concrete to withstand the exterior wall pressures caused by being below ground level. In addition, concrete can withstand moisture better than wood. So the majority of basement walls are made of either poured concrete or masonry blocks. Concrete basements typically have a poured concrete flooring system in what's called a slab.

Any movement of ground below or near the concrete slab floor can cause the massive slab to crack. That's why thick concrete such as that used in basement walls and floors is reinforced with metal bars called rebar. Exactly how much rebar is used and in what pattern depends on local building codes and the size of the slab. Some building codes allow a wire reinforcement mesh to be installed instead.

Because concrete is porous, moisture can come up through the floor (or through walls) ruining any flooring material you've installed. So preparing the subfloor for flooring materials means sealing it against moisture. It also means making sure the surface is level so that the flooring will be level.