MythBuster Monday! Tree Roots and Foundations

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Myth: Tree roots will crack my foundation and damage my underground pipes.



This is a concern we’ve heard many times, and a quick google search revealed that it’s a source of worry and confusion for plenty of tree- and home-owners. So, we took the time to do some research and get the facts.

Many people worry that the roots of large-growing trees will crack their pipes and foundations, but roots just aren’t strong enough! They will, however, take advantage of existing cracks.

There is certainly a lot of back-and-forth on this issue, with varying opinions about the amount of damage tree roots can do. However, the majority of sources, including Tree Canada and the Arbor Day Foundation, agree that tree roots CANNOT cause direct damage to foundations and pipes. Due to the enormous amount of pressure on foundations, tree roots just aren’t strong enough to actually create cracks in the concrete. When tree roots come into contact with foundations, they usually grow laterally along them, absorbing any condensation on the foundation surface. As for pipes: tree roots will only invade pipes that are already damaged and leaky. Roots are not doing the damage to the pipes themselves, they’re just an indication that its time for some maintenance. So in terms of direct damage, the story is pretty clear: tree roots are NOT the root of the problem.

However, some sources state that trees can damage foundations indirectly. Certain soils, like those high in certain types of clay, can shrink when moisture is removed. So, if tree roots suck up most of the water in the soil, which may happen during a drought period, this may cause the soil to shrink and lead to settling of the foundation. This settling, as well as heaving that can occur when the soil is re-wetted, can create cracks in the foundation.

Choosing a species suited to your conditions and watering your tree during drought will prevent the drying and shrinking of soil.

Since the soil shrinkage is most likely to occur due to trees trying to obtain enough water during drought, you can help prevent this kind of indirect damage by watering your tree and other vegetation during dry periods. Also, when planting trees, make sure they are a reasonable distance from your house. This not only keeps roots away from your foundation, but will also ensure the tree has adequate room to grow and doesn’t interfere with the house above-ground. Finally, choose species that are well suited to your soil and moisture conditions.

Remember that there are a number of other factors that can damage your foundation, so if you’re having problems, your tree is probably not the culprit! Trees do tons of wonderful things for us like provide shade, clean our air and water, reduce runoff, store carbon, support pollinators and improve our physical and mental health! So don’t deprive yourself of all of those benefits just because of your fear of tree roots – with proper tree selection and care, you can enjoy your tree without worrying about what’s going on below-ground.

One of our first Oakville Backyard Tree Planting Program participants is ready to enjoy the benefits of her new tree!

You can get your own backyard tree for a subsidized price through our Backyard Tree Planting Program. A certified arborist will consult with you to choose an appropriate species for your yard conditions while following LEAF’s minimum spacing requirements to ensure the tree has enough room for growth both above and below the ground. Sign up today at!

Read more:

Tree Canada – Planting Guidelines

Arbor Day Foundation – 8 Tree Myths Dispelled

JP Associates – Myth #3