Water Soaker Hoses for your Foundation: Don't waste your money
So, you bought soaker hoses or someone told you to buy soaker houses because your foundation is moving. Even worse, a so called engineer or home builder or warranty company told you that the reason your foundation is moving is because you are not watering the foundation and so you bought soaker hoses or you risk loosing your warranty.
We’re going to keep this explanation very short and using layman terms…for those of you who crave a little more technical language, please read Water Foundation science.
As many of you may know by now, clay soils expand and shrink with change in moisture content. In other words, when water is present in the soil, the soil will expand, therefore pushing up your foundation; when water is lost from the soil (i.e. when the soil gets drier), then the soil will shrink, therefore making your foundation settle.
When the weather is hot or dry, the soil will shrink, and when is cold or wet, the soil will expand. Throughout the year, the soil will naturally go through cycles of shrink and expansion. The depth at which the soil is naturally susceptible to moisture changes is called the active zone, which happens to be about 15 ft below the surface in San Antonio and Austin.
When designing a foundation, only natural events are considered. There’s no allowance in the building code for any water to be added unnaturally to the soil below the slab. The building code simply doesn’t talk about watering or not watering the foundation. It just says to design a foundation so that it doesn’t move from natural events (i.e. climate changes). There's nothing about soaker hoses in building codes or engineering text books on design of foundation.
Let’s ask ourselves some common sense questions: if the soil movement depends on moisture content (i.e. water content) in the soil, then how much water would you know to put without knowing the moisture content of the soil underneath your house? Also, assuming that somehow you are able to figure out the moisture content below you foundation, how much water do you know to put through the soaker hoses if everyday the temperature and rain/no rain conditions will change, meaning the moisture content in the soil will change also. One more question, how do you know that the water that you are adding through the soaker hose is changing the moisture content for a depth of 15ft below the foundation especially in view that clay creates an impermeable surface which tends to drain water horizontally more than vertically?
Just by thinking about these questions you will realize that there is no sound science that justifies buying and using soaker hoses. Yes, you might be able to change the moisture content of the soil, but you have no idea if it will work and if it does then by how much and how to change out the watering if temperature and environmental conditions change.
When someone tells you that your foundation moved because you didn’t use soaker hoses then that person is either not clear on the science or knows nothing about foundations. Many Engineers are not even structural engineers so beware of hiring engineers pretending to be Structural Engineers.
When a foundation moves, it’s because of the soil. And if it moves too much, it’s because of bad foundation design and/or bad construction or improper protection around the foundation perimeter. There’s simply no equation that accounts for “watering” or soaker hoses. Therefore, don’t let anyone –especially the warranty companies for the home builder- blame you that the foundation moved because you didn’t put soaker hoses. For more on foundation problems, please Foundation Repair San Antonio and Foundation Repair Austin
More questions? Contact your local office, we are and Structural Engineers San Antonio.