1. Surveying damage
The crawl space and basement foundation should be inspected for signs of flooding. Any water that has collected next to the foundation should be removed as soon as possible. Water left in the crawl space or basement can cause serious damage to the home's structure and foundation. Damaged items in a basement should be removed, and any items that have mold should be discarded.
2. Gutter check
Direct water runoff away from foundations. The No. 1 cause of flooding is inadequate or poorly maintained roof rain gutters. Rain gutters need to be inspected and maintained semiannually. All the runoff from the home's roof should be directed to the gutters. If they leak, are loose or are clogged, the water pours over or around the gutters and collects next to the foundation. As the water pours over the gutters, the soil next to the foundation erodes, allowing water to form pools instead of draining away.
3. Repair damage
Careful landscaping or French drains can correct poor drainage. Compacted clay soil, properly sloped next to the foundation and topped with planting soils, will divert water. The yard should slope at least 6 inches in the first 10 feet on all sides. If this is not possible, a French drain or swale can be installed. A French drain is a perforated plastic pipe buried beneath the soil and embedded in crushed stone. The pipe should be designed to drain by gravity to a suitable location. As water collects, it will soak into the French drain and be carried away. If you have splash blocks for downspout drains, install extension drains to direct runoff 6 feet from the foundation. (Splash blocks prevent erosion, but do not prevent pooling.
4. Sloping slabs
Inspect concrete slabs near the foundation: walks, driveways, porches and patios. These slabs must be sloped to drain away from the foundation. If the concrete is cracked and has settled, it should either be replaced or "slab jacked" to prevent flooding. Slab jacking is a process in which grout is pumped under the concrete slab to elevate the slab for proper drainage. Also inspect the landscaping between the foundation and the concrete slabs. Try to determine how rainwater from the landscaping will drain over the concrete slab. If you have landscape borders next to the concrete, the borders will act as dams holding the runoff water in the soil. There should be openings in them to allow accumulated water to drain.
5. Sloping soil
Make sure soil under decorative gravel or wood chips is sloped for drainage. Low areas that have been filled with gravel will form pools that can seep to the foundation. Window wells, access doors and foundation vents are openings in the foundation wall that are subject to flooding.
6. Rings of steel
"Area walls" can be installed to prevent flooding. They are semicircular steel rings that are available in various sizes to fit common-access door and window openings. For large area walls, plastic covers are available to keep direct rains out of the openings.
7. Ask an expert
If your water problems are severe, get help. A qualified home inspector can help you determine how to correct the problems. Find one at ashi.org.