Is concrete impervious to moisture and water?
No. Concrete can be made relatively impervious to both liquid and vapor water, but without these special preparation, both liquid and vapor water may move slowly through concrete. A common view is that a normal dried concrete slab-on-grade may pass in the range of 2 – 3 pounds of water per day per 1000 sq. ft. of floor. Experience has shown that indoor problems can be expected when the concrete water vapor transfer rate is in the double digit range.
