The answer depends almost entirely on circumstances and on the type of foundation that you have. On one hand, if you live in a home with a concrete foundation that rests on rock (say in the Texas hill country) you will never need a foundation inspection (happy thought!) On the other extreme, if you live in a pier and beam home in an area with high humidity and frequent swings between wet and dry periods, you may need annual inspections. Realistically, you only need to get a foundation inspection if you see problems, such as noticeable slopes in floors, sheetrock cracks, brick cracks, sticking doors, etc.
Here is a list of some of the most common conditions that contribute to foundation movement:
- expansive soils (some sort of clay)
- extreme seasonal swings between wet seasons and dry seasons
- large trees close to a home
- changing vegetation (rapidly growing trees)
- iron pipes
- high humidity
- a pier and beam foundation
The more of the conditions listed above that you have, the more likely you are to develop foundation problems. With multiple conditions present, you should pay more attention to signs of foundation movement and have your foundation checked more frequently.
Expansive clay soils shrink when they dry up and expand when they soak up water. As such soils shrink and swell, they move up and down (and when next to a retaining wall – sideways). As a result, buildings that rest on expansive soils move up and down. As long as movement is uniform or, in the case of nonuniform movement, does not result in a building suffering damage, there is no problem. Unfortunately for Texas, large portions of many major cities (Austin, Dallas, Fort Worth, Houston, San Antonio) are built on expansive clay soils.
Seasonal swings between wet and dry seasons play a huge role in causing foundation movement. There is a standard, named the Thornthwaite Index, that is used to evaluate moisture budgets. Unfortunately for Texas, Austin, Dallas, Fort Worth, Houston, and San Antonio are all located in areas with moderate to low values. Low values mean that there is a rough balance between rainfall and evapotranspiration. If an area is in balance and it has a significant difference in rainfall between a wet and dry season, then the stresses on foundations will be maximized. Dallas and Fort Worth have a zero value with a huge difference in seasonal rainfall. Austin, Houston, and San Antonio all have indices around 15 (the range for Texas is -40 to +40F.)
Trees use a lot of water. If you live in an area where there are significant differences in seasonal rainfall, then trees that use a lot of water during the summer can be a leading cause of foundation movement. The bigger the tree, the more likely it is to be a problem causer.
As trees go from immature to mature status, they grow, and so does their need for water. It is not uncommon for homeowners to live in a house for 30 years with no foundation problems, and to have problems develop with no warning. Often, the affected homeowners are perplexed, because from their point of view, nothing has changed. The gradual increase in the size of trees goes unnoticed. Large trees coupled with drought can cause movement.
Iron pipes were used in residences until the early to mid-1970s. After the mid-1970s, iron pipes were rarely used. PVC (polyvinylchloride) became the material of choice for drain pipes. Iron pipes had an original design life of 30 years. Today, the youngest of the residential iron lines are now 55 years old and most certainly leaking. Plumbing leaks can cause foundation movement, so homes with iron pipes do need periodic inspections, both of the foundation and the pipes.
High humidity is an issue for pier and beam homes, where lumber is exposed in the crawl space. High humidity promotes the growth of fungus, in particular dry rot, which can badly damage wood beams in the crawl space of a home. If a crawl space is poorly ventilated and subject to periodic wetting, then annual inspections should be made.
For many pier and beam homes, the interior of the home is supported on shallow concrete piers. The piers may simply be concrete pads, resting directly on the surface of the soil, that have concrete blocks stacked on them. Newer homes often have cast concrete piers that extend a few feet into the soil. In either case, the piers are easily moved by expanding or shrinking soils. If a crawl space becomes wet in the winter and dries in the summer, then seasonal movement can be a real problem.
Here is a short case study. Around 1995, a homeowner in south Arlington had his foundation checked. Around one wing, there were three live oaks, all less than 6 inches in diameter, and perhaps 15 feet tall. The homeowner was advised to remove the trees, which he did not do. The home was rechecked every 5 years. By 2015, the trees were all 15 to 24 inches in diameter and over 40 feet tall. The foundation had settled 2.5 to 3 .0 inches in the areas by the trees. Repairs were made to the foundation and the plumbing at a cost of nearly $20,000. The homeowner did not regret keeping the trees, which he enjoys to this day.
Sometimes, it is pretty obvious when your house has had foundation movement. Whether or not there has been related foundation damage is often not so clear. To ensure your home stays safe and sound for you and your loved ones, it’s important to leave this work to the professionals. Contact Advanced Foundation Repair today for a free, precise inspection. With years of experience, a transferable lifetime warranty, and the willingness to work with you on a payment plan to make sure your home gets the repairs it needs, you won’t be disappointed.