As a homeowner, there are few sights as sickening as a finished basement filling with murky brown water. Construction engineers cite "moisture intrusion" as the No. 1 reported complaint with newly constructed homes [source: Roney]. Some flooding is unavoidable, the result of torrential storms and swollen rivers. But in many cases, basement and crawlspace flooding isn't Mother Nature's fault; it's the contractor's.
There's no such thing as a waterproof foundation [source: Building Science]. If water builds up around foundation walls, hydrostatic pressure will eventually force the moisture through inevitable cracks and fissures. With the right design and materials, however, a quality contractor can keep water away from foundation walls altogether.
A dry basement starts with careful grading of the property. If a contractor is in a hurry, he or she may not take the time to bulldoze soil so that water always flows away from the house rather than toward the foundation. Next, you should install roof gutters and downspouts that corral rainwater far away from the base of the home. If rainwater is allowed to run directly from the roof to the ground, it will pool up right next to the foundation wall. In a rushed construction job, downspouts are easy to overlook, but they could lead to costly damage.
Below the surface, foundation walls need to be cushioned by a thick layer of free-draining backfill, usually gravel. When water flows freely, it drains straight down, rather than seep horizontally. The loose gravel ensures that all groundwater flows directly down toward a subterranean drainage system. The system is a perforated drainpipe that lets water in from the top, and then whisks it away to sewers or a sump pump [source: Building Science]. Failure to lay the right fill material can lead to flooding, even in high and dry areas.