Standing water under the house is not normal

Sellers tell us it always does that after a storm. Sometimes that is true, and it is still not normal. A crawlspace that holds water is telling you something about where the water is coming from, and the answer is nearly always one of three things.

Grading

Soil should fall away from the house — roughly six inches over the first ten feet. Flower beds, new patios, and years of mulch all quietly reverse that slope, and once it is reversed the crawlspace is where the yard drains.

Downspouts

A roof sheds a startling volume of water. Concentrating that at the foundation through a downspout with no extension will beat any grading you have. This is the cheapest repair on the list and the one most often skipped.

A plumbing leak hiding behind both

If the water is present in a dry week, it is not rain. A supply line weeping under the house looks exactly like a drainage problem until someone checks the meter with every fixture off — which takes about ten minutes.

Why it matters

Standing water raises the humidity under the floor, and sustained humidity is what rots framing and brings in the pests that finish the job. The correction is usually a few hundred dollars of dirt and pipe. The consequence of leaving it is a structural repair, which is the most expensive way to learn about drainage.