Is Watering a Foundation a Myth?

Are you wondering if watering a foundation is a myth? If by "myth" you mean something ineffective or something you shouldn't do, it's complicated. In other words, you're going to hear various opinions on this. What we're going to present here is our opinion only. Keep in mind that we're in Nebraska, not Texas, a state where you'll often hear advice about watering a foundation because of the hot, dry weather there.  We offer our opinion on whether or not you should water a foundation not as the final word but as something we'd like you to consider. We do understand the effect drought can have on a foundation, as well as the problems caused by excess water in the soil around a foundation. So, before we dive in, we need to clarify not only how hot, dry weather can affect a foundation, but how water can affect a foundation as well.

How Hot Dry Weather Can Affect a Foundation

During hot, dry weather the soil dries and shrinks. If you have expansive soil (soil with a lot of clay in it), this shrinkage will be especially pronounced, and it could cause voids to form under the foundation. If the foundation sinks into the voids, the home will experience differential settlement which can cause serious structural damage to a foundation. (See the graphic below.)

How Water Affects a Foundation

Water is the cause of most foundation problems. When there's too much or too little of it in the soil around and under the foundation, things go wrong. Before we explain how things go wrong exactly, let's talk more about expansive clay soil, one of the most problematic soils for construction.

What is expansive soil?

Expansive soil has a lot of clay in it. It swells when it soaks up moisture and shrinks when it dries out. Depending on how much clay is in the soil, the soil can swell and shrink by quite a bit.

What happens when a foundation is built on expansive soil?

Expansive soil swells when there's excess water in the soil. This creates movement under the foundation. When the soil dries out, it shrinks, again creating movement under the foundation. This swelling and shrinking cycle - which is usually seasonal - puts a lot of stress on a foundation and will, over time, cause differential settlement.   If you have a basement foundation, excess water in the soil along with poor drainage - common with expansive soil - creates a build up of hydrostatic pressure that pushes against the foundation wall. If the pressure isn’t relieved, the wall could bow inward and even crack.

What happens when a foundation is built on expansive soil during hot, dry weather?

During a drought, expansive soil dries up and shrinks under the foundation. Voids form, and the foundation eventually starts settling into the causing differential settlement. This is why you'll hear recommendations to water a foundation. The theory is that adding water to the soil will prevent it from drying and shrinking, and we agree with that.

Is Watering a Foundation a Myth?

As mentioned above, if by “myth” you mean something incorrect or something to be avoided, no. We do not see watering a foundation as a myth. We see value in watering a foundation to keep expansive soil from drying out. However, you’ll need to use caution, and here’s why: If the soil around the foundation is already dried and cracked, watering the soil too close to the foundation could cause the water to run down the foundation wall. If there are any cracks in the wall, even invisible ones, water could get into your basement or crawl space.

Water at least 18 “-24” away from the foundation and let the water soak in laterally and vertically. Hopefully, this will avoid directly introducing too much water to the foundation.

Don’t water for too long. If you add too much water to the soil, you risk increasing the hydrostatic pressure to such a degree that it will put lateral pressure on the foundation. As we mentioned above, this could cause bowing or cracking. So, avoid watering for longer than one hour and make sure the spigot isn’t opened up all the way. You want a nice slow soak into the soil.

For more information about hydrostatic pressure, see Is Hydrostatic Pressure The Reason You Have a Wet Basement?

Things Homeowners Can Do That Will Help Prevent Foundation Problems

Here are some things you can do that may prevent problems with your home's foundation. Notice they all involve getting groundwater around your foundation under control:

• Regrade your yard, if necessary - Since you don't want water to drain toward and pool around your foundation, the yard should slope away from the foundation. If it doesn't, have it regraded by a landscaping professional. You could also do this as a DIY project.
• Make sure you clean your gutters regularly - If your gutters are clogged, water will spill over the side of the house and soak into the soil around the foundation. You don't want this since you're trying to keep excess water away from the foundation.
• If your downspouts are too short, install extensions - Downspouts should channel water at least 10 feet from the foundation before releasing it. If yours are too short, extensions are inexpensive and easy to install.
• Install an underground downspout and a pop-up emitter - An underground downspout connects to the pop-up emitter situated several feet away from your foundation. When the pop-up emitter fills with water, it pops up and releases the water.
• Keep large trees at least 20 feet away from the foundation - Large trees can have extensive root systems bigger than their canopies — the tree roots "drink" water from the soil, creating voids under the foundation.
• Install a drain tile system - You can't beat a drain tile system for controlling groundwater around a foundation. There are two types of drain tile systems, exterior, and interior. They both work by preventing excess water from building up in the soil. For more information about how they work.
• Install a French drain in your yard - A French drain works similar to a drain tile system, except it's situated in your yard instead of next to your foundation. It involves placing a perforated drainage pipe in a shallow trench and covering it with gravel and soil. Excess water flows into the pipe and gets released away from the foundation.
• Ensure your plumbing isn't leaking - Undetected plumbing leaks can add quite a bit of water to the soil around the foundation.

If you have concerns about the soil around your home's foundation and you're in our service area in Lincoln, Omaha, Grand Island, Kearney, Nebraska, Missouri, Iowa and parts of Northeastern Kansas, contact us today.