Protecting Texas Foundations

Foundation Maintenance Program

Soils of the North Texas area contain highly active clays which exhibit a high degree of expansion when wet and shrinkage when dry. This situation can result in severe vertical and/or lateral displacement of supported structures. Repeated variations in soil moisture content cause differential movement and undue stress to structural elements of a building, resulting in broken and unlevel floors, masonry cracking and misalignment of doors and windows. Consistent soil moisture content is key to controlling these problems. In this week's article I provide a guide to identifying problem areas and offer solutions that will help you protect your home.

Maintain Good Drainage

The illustration below shows in a graphic form how the grading should be around a home. You can see that the sloping grade directs the water to the swales which in turn channels the water away from the foundation. Ideally you should have a slope around your foundation of 6” in the first 10’. 

Avoid Water Traps

Avoid trapping water against your foundation.  Water can be trapped against the building by raised flower beds, using metal edging or other borders that do not have openings to allow water to escape, by sidewalks or other obstructions.

A common problem is poor gutter down pipe design leading to erosion and moisture build up. This illustration shows a gutter emptying next to the foundation which will cause problems over time. The solution is to add gutter down pipe extensions as shown.

However, the very way in which your home was built can cause a problem. In the photograph below, water run off from the roof is pooling in the area below and the foundations on either side are trapping it.

To remove large volumes of water you may have to install a French drain. The general construction of a French drain is shown in the following illustration.

Trees and Shrubs

If you have large trees around your house, and the trees are closer to your foundation than the height of the trees, consider installing root barriers to keep the trees from pulling water out from under the foundation. Large trees or shrubs can consume tremendous amounts of water and should not be planted next to the foundation. When planting these items, be careful that roots of mature trees do not extend beneath the foundation. Trees can cause settlement and invade your drains, all of which can lead to costly repair bills.

Avoid Low Moisture Levels

Whenever cracking of soil occurs or soil is noted to be pulling away from the foundation, it is an immediate signal that soil moisture levels are too low. Water should be added in a slow, systematic manner using an automated sprinkler system or a soaker hose placed 18 in. from the foundation with holes facing downward. Water should be applied until runoff is observed. During hot weather, this process should be repeated four to five times weekly - less during winter months. In summary, remember that a consistent moisture control program will minimize soil movements, resulting in less stress and longer service life of the structure.