When you install hardwood flooring in your basement, on top of concrete, you need a floor vapor barrier in between the concrete and wood. If you install the hardwood flooring directly on the concrete, moisture from the soil will seep through and penetrate the wood. This causes warping and mold. Vapor retarded paint costs around $20 to $40 a gallon, and a gallon will give you nearly two coats of protection. Costs vary when using the 8 millimeter plastic sheeting, depending on the size of your room. A square foot of plastic sheeting costs around $.25 to $2.50. This is a tiny fraction of the cost if you don’t preemptively protect your basement from moisture. Moisture can cause many problems not just with the wood flooring but also to your basement foundation, as well as your basement environment in general.