Water damage that occurs in the basement may have its beginnings in the landscape surrounding the house. While basement flooding may occur from indoor sources like a broken plumbing pipe, or from naturally high underground water beneath the house, excess water saturating the soil immediately around the perimeter of the home can also slowly leak into the basement through structural cracks and other openings. Avoiding over-saturation of the soil as well as diverting accumulating water away from the house are landscape considerations that can help reduce outdoor causes of indoor water damage down in the basement.
- Grade the ground. Landscape sloping toward the house—a condition known as “negative drainage”—causes rainwater and water from sprinklers or other sources to accumulate near the house and saturate deeply into the soil, potentially causing water damage by infiltrating basement walls. Soil adjacent to the foundation should be sloped downward away from the house at least four inches over the first six feet of horizontal distance.
- Keep big vegetation away. Large shrubs and/or trees attract and retain considerable water in the surrounding soil. To prevent this water from entering a nearby basement or foundation, these large plants should not be planted closer than three feet from the wall of the house.
- Detour the water. Certain areas of the lawn near the house may tend to retain excess water after rain due to the type of clay present in the soil. To prevent potential water damage to the basement, create a one-foot deep trench with gently sloping sides to collect and reroute the water to another part of the lawn further away from the house. Once replanted with grass, this shallow depression will not be visually conspicuous nor interfere with mowing.
- Grass is good. The specific root structure of grass very efficiently absorbs water from the soil and contains it. Planting grass close to the house is therefore an ally to prevent basement water damage. Once the grass matures, avoid cutting it too short, which weakens roots and diminishes water absorption.
