Proper maintenance of your home’s foundation and supporting soils is critical in the prevention of foundation failure. Each Design Tech home is supported by a monolithic slab-on-grade foundation. Slab-on–grade foundations are 100% dependent on the underlying soils for support. Although every Design Tech home foundation has been professionally engineered for the type of soil in your area, like most other components of the home, it requires maintenance. Your foundation, with proper care, was designed to support the home throughout its functional life.
Most areas of Texas have soils that contain various amounts and types of clay. While clay soils can have great bearing capacities, they tend to expand and contract based on moisture content. Since it is not possible to control rainfall, we could never hope to maintain clay soils in a “contracted” state. Therefore, the goal of this document is to help you maintain these clay based soils in their “expanded” state.
Please remember there is a huge difference between foundation movement and foundation failure. All slab-on-grade foundations move to some extent. In fact, they are designed to move. Most of the foundation movement associated with expansive clay soils occurs within the first 2 years of the home’s completion. Typically the movement stops when the foundation establishes its “footprint” in the underlying soil.
In some instances the foundation movement can result in cracks in building components such as stucco, sheetrock, tile, brick, molding, etc. These cosmetic damages do not preclude the diagnosis of “foundation failure”. Quite the contrary, it is extremely unusual not to have some cosmetic repairs associated with foundation movement within the first two years of home ownership. However, proper foundation maintenance can greatly reduce the need for cosmetic repairs.
It is the builder’s responsibility to establish proper drainage around the foundation perimeter. Although we want the perimeter soils to be hydrated, they must be hydrated uniformly. Therefore, the builder will establish positive drainage away from the foundation at all points around the foundation perimeter. Water cannot be allowed to pond at any point adjacent to the foundation.
You will possess the home much longer than it took to build. Therefore, more long-term maintenance will be required of the homeowner. Please remember that the foundation is the most expensive single component within the home. Like most other components of the home, it requires proper maintenance. Here are the basic steps:
1.) Grading and Drainage:
You are responsible for maintaining the positive drainage established by the builder. While proper grading and drainage is important in all soil conditions, it is critical in areas with expansive clays. There should be at least 4 inches of the foundation showing above the grade at all points of the foundation perimeter. In addition, the soils adjacent to the foundation should slope away from the foundation for at least the first 6 feet. No alterations to the established grading should be made. Landscaping and soils that are added should not interfere with the established lot drainage. Ponding water adjacent to the foundation may cause serious structural damage and affect the warrantable status of your foundation.
Ironically, while we address the importance of removing surface water from the foundation perimeter in item#1, we also need to address adding water to the foundation perimeter. The key to proper hydration is uniformity. That’s why we can’t rely on intermittent rainfall for our hydration. Therefore we remove rain and surface water, then rehydrate in a very controlled and uniform manner. By adding water evenly to the soil along the foundation perimeter, we can mitigate the contraction that occurs during drought conditions. In clay soils you should be able to press a pencil into the ground about 4 inches with relative ease. You don’t want the soil to be muddy or excessively soft, but it shouldn’t be like concrete either. If there is a gap between your foundation and the adjacent soil it means you need to add water…..evenly….at the entire perimeter of the foundation!
3.) Trees, shrubs and other large vegetation:
Please think carefully about the size, type and location of the trees and shrubs you are planting. The small oak tree you plant today will be quite large in 20 years. A 25 year old oak tree will need up to 100 gallons of water per day to survive. That’s not a problem if you plan ahead for meeting this need. But if you don’t give it enough water, it will simply take it…from under your foundation or your neighbor’s foundation. When trees are removed near a foundation, approximately 70% of the roots are penetrating under the slab….because that’s where the water is located! Never plant a large tree closer than 25 feet to your foundation. In addition to the problems caused by the roots, the canopy will also cause damage to the superstructure. Large shrubs should also be planted at least 6 feet from the foundation. These plants can steal vital moisture from the soils which support the home. Flower beds and other landscaping should never impede the grading and drainage established by DTH.
One of the wonderful things about dogs is that they love to dig. That’s not a problem unless they are digging adjacent to the foundation. It only takes a small amount of ponding water adjacent to the foundation to cause problems in expansive soils.
5.) Utilities, construction and repairs:
At some point in the life of a home it will become necessary to make a repair or install a utility. If the construction involves trenching adjacent to the foundation, it should be done with great care. Just filling a construction trench with loose fill will allow water to be trapped adjacent to the foundation. It is your responsibility to make sure the trench is properly compacted during backfill. A licensed structural engineer should be consulted prior to making any major additions to the property. Swimming pools must be designed as not to undermine the underlying soils which support the foundation. All additions must include a drainage plan that will keep surface water from ponding adjacent to the foundation.
Plumbing leaks can wreak havoc on a home’s foundation. Soft or muddy areas in the soil, “heaved” areas inside the home, excessive moisture coming from weep holes in the brick and wet areas within the dwelling can all be signs of a plumbing leak. If you find any of these conditions, please call a plumber or the warranty department for assistance immediately.
Know your home. By keeping an eye on things, most problems can be repaired before they cause major damage. When mowing, it is a good time to visually inspect the exterior of the home. If you have your lawn serviced by someone else; take the time to walk the exterior of your home at least once a month. Look for anything out of the ordinary. Anomalies in the siding, caulking trim, etc. may be early indicators of foundation movement. Your home will usually let you know when something’s not right! Contact DTH if you believe your foundation is moving abnormally.