How to Stop Tree Roots From Growing Under House

Tree roots growing beneath your home can cause damage to the foundation, destroy plumbing, or ruin sidewalks and driveways. In these cases, it’s important to know when you can safely cut tree roots, when you need to remove the tree, and when you can use chemical herbicides or root barriers to stop root growth and protect your home.

Using these methods, you can halt tree root damage, begin to repair it, and prevent harm from invasive roots in the future.

How to stop tree roots from growing under house

Signs of Tree Root Damage to Your Home

There are several ways to identify that invasive tree roots near your home are causing damage. In order to determine if a tree is causing a problem to your house or other structures, look for the following signs when a tree is within 30 feet of your home:

  • Vertical cracks in the foundation.
  • House slants toward the tree.
  • Pipes that are clogged or slow to drain even when they have been snaked and cleared.
  • Sidewalks or driveways buckling

Trees pull moisture out of the soil. This may not seem like a problem at first, but a thirsty tree planted near your home can strip moisture out of the ground. This in turn draws moisture out of your foundation, causing cracks to form. This also may make your house lean toward the tree. As the dry soil settles faster than soil that isn’t invaded by roots, the side of the house closest to the tree will sink.

Types of Home Tree Root Damage

Once tree roots have become a problem, it’s time to act. There are three main ways in which tree roots can damage your home:

  • Foundation: Damage to the foundation of your house and other structures.
  • Plumbing: Invading water lines, sewer lines, and septic systems.
  • Paved Surfaces: Buckling concrete and paved surfaces.

All of these are common problems, and in some cases, a particularly invasive tree can be responsible for all three at once. Here’s how to battle each one of these cases.

How to Stop Tree Roots From Damaging Your Foundation

Is your home showing signs of damage on the side of the house closest to a tree or bush? This damage often takes the form of vertical cracks in the concrete foundation. In the worst-case scenario, roots have even begun to physically invade these cracks. Here’s how to solve the problem.

  • Cut Tree Roots: Excavate a trench along the foundation to a depth of 18 inches. Cut all tree roots in this area and remove the cut ends if possible. This can be done as long as the roots are more than 15 feet from the main trunk and only makeup about 25% of the tree’s root system.
  • Install Root Barriers: After successfully cutting tree roots, it’s critical to prevent new root growth from growing under your house again. Use this root barrier as protection. Place it in the trench you dug when cutting roots. Then, backfill the trench to keep the barrier upright and in place against your foundation.
  • Remove the Tree: If the tree is close to the house (less than 30 feet for large trees like oaks and maples, 15 feet for smaller trees) and/or cutting invasive roots requires you to trim over 25% of the tree’s roots, it’s best to remove the tree. Extensive root trimming close to a tree’s trunk can result in sickness and death, and may cause the tree to fall on your house. Contact an arborist or remove the tree near your house yourself.

It’s important to note that cutting the offending roots isn’t always the safest solution for invasive root growth. Remember, tree roots damage the foundation by pulling moisture from the surrounding soil. This means that roots don’t have to penetrate the foundation to crack, damage, or cause it to lean. Not only is root pruning only minimally effective, but when you trim roots you risk killing the tree. This could invite termites or cause the tree to fall on your house. If root trimming doesn’t kill the tree, the roots can grow back and continue to harm your home.

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How to Stop Plumbing Damage Caused by Tree Roots

When a tree sends roots near or beneath your home, it’s typically looking for water. Once tree roots find a water source, they grow aggressively. Often, tree roots will find cracks in water or sewer lines, then grow quickly to clog them. If your septic system or plumbing is attacked by tree roots, use one of these methods to kill them:

  • Dichlobenil Herbicide: This foaming root killer can be poured into a toilet and flushed or poured into a septic cleanout pipe. Once inside your plumbing, the Dichlobenil herbicide will quickly attack tree roots and kill them. After the roots are dead, the bacteria in the plumbing system will cause the roots to decompose, unclogging your pipes.
  • Copper Sulfate: An alternative to Dichlobenil is this copper sulfate root killer. Much like herbicidal products, it can be flushed into the system through a toilet or added directly to septic systems. Copper sulfate is toxic to roots and will kill them fast.
  • Natural Flushable Root Killer: Mix 1 cup of salt with 1 cup of baking soda, then, add 1 cup of boiling water. This mixture will foam rapidly, so be prepared to pour it into a downstairs toilet and flush quickly. The foaming baking soda will help distribute the salt through the pipes, where it can attack invasive tree roots. This mixture can also be used in sinks and other household plumbing invaded by roots.
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With all these products, wait 8–12 hours after adding them to the system before flushing the toilet again, if possible. It’s best to use these solutions just before you leave for work, or at night just before sleep. This will allow the product to work uninterrupted.

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How to Stop Roots from Damaging Your Driveway

Because driveways, sidewalks, and other paved surfaces are shallower than foundations there is an increased chance that roots will work their way beneath. This buckles concrete, asphalt, and paver stones. In order to control these roots:

  • Cut Roots and Install Root Barriers: As you would with roots that invade foundations (see above) dig an 18-inch deep trench alongside your driveway and cut any roots tunneling beneath the driveway. Then, install root barriers to prevent roots from returning.
  • Remove the tree: If cutting roots that tunnel beneath your sidewalk requires you to chop roots 2 inches in diameter (for trees over 15 feet tall), then you are cutting significant roots from your tree. This kind of damage could potentially kill the tree or make it prone to falling. If a large tree is within 10 feet of the paved surface, consider removing it entirely. It may be dangerous to cut the roots.
  • Repair Paved Surfaces: Once the offending roots have been cut, or the tree has been felled and you’ve killed the stump and roots, you’ll still be left with a buckled driveway. To repair it, you can bust out a portion of concrete, remove the root beneath, and repave the area. Alternatively, you can patch the jagged area with asphalt for a less expensive fix.

In many cases, tree roots that lift concrete and paved surfaces are not dangerous to your home, just unsightly. Decide whether or not you can live with the root damage. It can be easiest and safest to leave the tree as-is.

Which Trees Damage Foundations?

Many species of trees are great for your yard and will not send invasive roots into your foundation. Oaks and sugar maples are beautiful and safe trees when planted at least 30 feet from your house. However, some trees are extremely invasive and can send damaging roots into your foundation from upwards of 50 feet away. Avoid planting the following tree species:

  • Norway Maple
  • Silver Maple
  • Willow
  • Poplar
  • Cottonwood
  • American Elm

Each of the above trees is notorious as a water hog that will seek out plumbing or naturally has extremely invasive root systems. When planting a tree or considering tree removal, take the time to determine the tree species.

How Do You Kill Tree Roots Near Your Foundation?

In order to get rid of invasive tree roots growing beneath your house, there are a few means of defense. These are:

  • Excavate an 18-inch deep trench along your foundation and cut any tree roots you find.
  • Install root barriers to prevent trees from sending roots under your house.
  • Remove the tree entirely.
  • Use Dichlobenil, copper sulfate, or salt-and-baking soda products to kill roots in plumbing.

These methods will help you kill invasive tree roots and reclaim your home. When you have a problem tree, act fast to prevent structural damage and preserve your house.

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