The Link Between Foundation Damage And Excess Soil Moisture

The Link Between Foundation Damage And Excess Soil Moisture
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Believe it or not, the number one cause of foundation trouble revolves around moisture in the soil. When foundations are built atop certain soil types, too much or too little moisture is a bad thing. Here’s why…

Not all soils are alike. Some are better suited for construction than others. The most problematic soil types for construction are expansive soils that swell – often by a considerable amount – when they soak up moisture and shrink when they dry out. This is usually seasonal and creates movement under the foundation as the soil expands and shrinks. This movement puts a lot of stress on the foundation and eventually leads to foundation problems.

So, if you want to lower your risk of foundation damage, you can start by controlling ground moisture.

For more information, see California Drought And Your Home’s Foundation.

What causes foundation moisture problems?

Most foundation moisture problems are caused by excess water in the soil around the foundation. But, where did the excess moisture in the soil come from? Here are a few ways water can build up in the soil around your home’s foundation:

  • Poor drainage – Water around your home’s foundation needs a way to drain off. If it can’t drain off, the soil will get saturated and cause trouble with the foundation. For example, if you have a basement foundation, hydrostatic pressure will build up in the soil and start pushing against your basement walls. This could lead to leaks, bowing, and even cracking—more on this below.
  • Rain – Excess rainfall along with poor drainage is going to lead to foundation moisture problems.
  • Melting snow – See above.
  • Plumbing leaks – Plumbing leaks can go undetected for a long time and contribute to excess moisture in the soil around and under the foundation.
  • Yard not graded correctly – Your yard should slope away from the foundation, not toward it. You don’t want water pooling around the foundation and soaking into the soil.
  • Water-hungry shrubs, flowers, etc., next to the foundation – When you water them, you’re adding water to the soil around the foundation.
  • Clogged gutters – If your gutters are clogged, water may spill over the side of your home and into the soil.
  • Downspouts that are too short – Downspouts should deposit water away from the foundation. If they’re too short, install downspout extensions.

    Foundation trouble can also be caused by not enough moisture in the soil. For example:

  • Drought – Drought causes soil shrinkage, which leads to the formation of voids under the foundation. If the house sinks into the voids, you’re going to have problems.
  • Large trees – The root systems of large trees will “drink” water from the soil, leading to voids. Large trees should be at least 20 feet away from the foundation.
california drought soil

Wet basements and excess foundation moisture

Wet basements are common and are usually caused by excess moisture in the soil around the foundation. When hydrostatic pressure builds up in the soil outside the foundation walls, it can push moisture through the wall. It can also cause the wall to bow and even crack.

Basement foundation moisture can lead to:

  • Mold growth
  • Unpleasant odors
  • Health problems – A certain percentage of air from your basement flows up into your home’s living area. If the basement air is full of mold and other allergens, the air in your home will be as well.

Signs of excess foundation moisture in your basement include:

  • Pooled water on the floor – This is a sign that’s hard to miss.
  • Water coming through the foundation walls – This might be just a trickle.
  • A ring of moisture at the base of the foundation walls
  • Condensation – The condensation could be on the walls, floor, or items stored in the basement.
  • Unpleasant odors – Does your basement smell musty?
  • Wood rot or deterioration of cloth items such as carpet or furniture
  • Water stains
  • Blistered paint
  • Humidity

Of course, there are other sources of moisture in the basement, including showers, cooking, dryers, and open windows that allow warm, humid air to condense on cool surfaces.

If your basement is wet, you can’t live in it or use it to store valuables.

How to prevent foundation moisture problems

Fortunately, homeowners can prevent foundation moisture problems by getting groundwater under control. Here are some ways to do that:

  • Good drainage is key – If there’s no excess water in the soil around your foundation, hydrostatic pressure can’t build up and start pushing against basement or crawl space walls.
  • Regularly clean your gutters – Clogged gutters cause water to spill over the side of your house and into the soil.
  • Install downspout extensions – Downspouts that are too short will release water next to the foundation. You don’t want that. Extensions are easy-to-install and will carry water away from the foundation before releasing it.
  • Install an underground downspout along with a bubbler pot – Water flows from the gutters into the underground downspout and from there into the bubbler pot, located several feet from your foundation. When the bubbler pot fills with water, it pops up and releases the water away from the foundation.
  • Ensure your yard is graded correctly – Your yard should slope away from the foundation so that water doesn’t drain toward your home.
  • Install a drain tile system – A drain tile system is a foundation waterproofing gold standard. It works by preventing excess moisture from building up in the soil around the foundation.
  • Don’t plant water-hungry shrubs next to the foundation – When you water them, you’ll just be dumping water around the foundation.
  • Keep large trees at least 20 feet away from the foundation – This isn’t related to excess moisture in the soil around the foundation but rather too little water. Large trees “drink” water from the soil, which can dry out the soil and lead to the formation of voids which the foundation will sink into.

For more information, see Foundation Settlement.

Because there’s a connection between foundation damage and excess soil moisture, homeowners should do what they can to get groundwater under control. Doing this costs less than repairing a foundation.

If you’re having trouble with excess foundation moisture and you’re in our Northern California service area, contact us today for a free inspection and repair estimate.

Steve Egloff

Steve Egloff

Steve is the CEO at Bay Area Underpinning, a foundation repair contractor serving the San Fransisco Bay Area, California. Bay Area Underpinning was founded in 2005 with the goal of providing a cost-effective, engineered solution to foundation settlement problems with an emphasis on educating customers to make them feel comfortable with the various methods of foundation repair.

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