Flowerbeds, landscaping and vegetation, such as trees and shrubs need to be evaluated to assure adequate distribution of moisture around the foundation of your home. Trees and other large plants can significantly contribute to unequal settlement of a foundation. The roots of trees and large plants consume the moisture from the soil, causing the soil to shrink faster than other areas. This loss in moisture can cause the areas closer to the trees and foliage to shrink more rapidly than other areas of the foundation.
Diligent attention to the placement of foliage around your house will help prevent future foundation problems. The first step is to plan ahead. Trees and bushes should be planted at an adequate distance from the house. A tree should be at least as far away from a building as the height of the tree when fully grown in order to minimize the effect of drying.
For houses that have existing large trees or bushes near a home, you should cut and cap the roots of any large trees growing closer to the foundation than the mature height of the trees. It is recommended that a professional tree expert be used to prevent damage to the trees. When a tree grows too close to a building to allow cutting and capping of the roots, it is advisable to remove the tree or make special provision for watering the soil below the foundation.
An ample amount of water should be provided to large trees surrounding your foundation. High growth of dense vegetation near the foundation should be avoided. The watering of the trees, especially in dry periods, will prevent a situation of uneven moisture content in the soil beneath the foundation. Remember, differential moisture content – adjacent areas of soil with different moisture content – can cause home foundation problems. Keep in mind that moderate to large trees consume 50 to 75 gallons of water from the soil every day.
Water from flowerbeds should be carefully diverted away from the foundation. Ground elevations of the surrounding flowerbeds should be maintained so that the slab is at least two to four inches above the finished ground, and the flowerbed should be sloped away from the slab for proper drainage. This will also prevent the seepage of moisture into the wall system or inside the residences through weep holes in the brick veneer walls. This is the most common mistake of homeowners and landscapers!