Unfortunately, far too many construction and floor covering professionals adhere to fallacious assumptions regarding concrete and moisture-related problems. In this article, I'll identify some common misconceptions about concrete that can really get you into trouble.
It's the concrete guy's fault. The concrete contractor usually follows the specification written by the architect, so blaming the contractor for a moisture problem is really unfair -- unless the driver of the cement mixer adds excessive water to the mix or the finisher pokes holes in the vapor retarder, which are two practices that occur often and can cause moisture-related failures. Instead, today's fast-track construction practices are most often to blame because the buildings are completed before the slab has had a chance to dry sufficiently. Often, floor coverings are installed over concrete that is not yet dry. Frequently, flooring is laid before the heating and ventilation system is operational, which can lead to problems later when the excess water vapor in the concrete is drawn upward through the slab surface by the dry conditioned air.