Nothing makes a hike in the woods or a walk in the park quite as nice as the beautiful landscape dotted with towering trees. Trees provide us with shade, oxygen, air purification, and they’re just nice to look at, especially in the fall! But, what we might not realize is that much of the tree lies underground, and beneath the soils lies a problem waiting to happen.
Tree roots can damage building foundations, as well as sidewalks and pavements. The most common trees that damage building foundations include Norway maples, silver maples, oaks, ash, poplar, walnut, cottonwood, and sycamore trees. These trees have a high potential to do damage underground.
There are a few things that make your foundation more susceptible to root damage. But rest assured, there are ways to mitigate and even prevent roots from approaching your foundation altogether.
Can Trees Affect House Foundations?
Before we talk about the specific trees that can cause damage, let’s discuss the damage itself. How exactly do trees affect your home’s foundation?
According to the Wyoming Department of Public Works, up to 90% of tree roots are found in the top 12 inches of soil. Foundations range in depth from a few inches below the surface to a few feet.
Needless to say, your foundation is right in the target zone of grasping roots.
There are two main ways that roots cause damage to your foundation. They will either lift your building up, causing cracks, or they will shrink the soil, which causes the foundation to settle.
Trees Can Lift Up House Foundations
The first way that roots can damage your foundation is by causing your home to lift up slightly. This puts pressure on the foundation, which can buckle and crack.
Roots on a healthy tree will grow annually, just like the trunk does. Purdue University states that, normally, when a root hits an impenetrable object (your foundation) they seek to go around instead of under.
This is especially true because the soil beneath your foundation is probably compacted from the original construction and dried out due to the cover over the soil.
However, some roots are stubborn and are determined to go under your foundation, or through pre-existing cracks.
As the roots continue to grow, they will take up more and more space beneath your house, literally lifting the building by tiny fractions.
This phenomenon is a lot less common than other root issues. You are more likely to find roots growing along your foundation than beneath it.
Trees Can Cause Soil Shrinking Near Foundations
The more common way that roots damage your foundation is by shrinking the soil. So, how exactly do roots shrink the soil?
Roots will look for the most advantageous path to grow. This means plenty of moisture, loose soil, and lots of nutrients. While this doesn’t normally cause a problem, roots that make their way into clay soils can significantly alter the height of the soil when they come through.
Clay soils have a peculiar property where they can hold a ton of moisture. But, when that moisture is gone, clay soils tend to shrivel up and, you guessed it, shrink!
So, when roots are sucking in all the water they can get, they’re actually shrinking the soil around them. This, in turn, causes the foundation to settle. In the process of settling, cracks can form in the foundation.
Most Common Trees That Damage Your Foundation
Whether you’re building a new home or buying an existing home, you’ll want to take a close look at the landscape. What kind of trees do you see?
If you’re not sure, you can always use something like the National Wildlife Federation Field Guide to Trees to help you figure out what you’re looking at!
Some trees are more prone to damaging foundations than others. According to Michigan State University, trees that are fast growers above ground are often growing just as fast belowground.
These are the trees that you want to look out for because their roots will be far- and fast-reaching. Let’s get into it!
Oak Trees Damage Foundations
Oak trees aren’t as common in landscapes as other trees, but despite this, they tend to cause the most damage to homes.
There are plenty of different oak tree species, about 90 in the United States alone. They’re typically considered slow-growers, but they are massive, many species being able to top out at 100’ or more.
These enormous oak tree organisms are held in place by a deep taproot that shoots directly beneath the trunk. As the tree grows, lateral roots take hold and begin snaking out from the tree in all directions. These roots can reach as far as three times the height of the tree.
In addition to being a danger to your foundation, some oak species are prone to limb drop. If you have an oak tree in your yard and a limb is hanging over your house, it’s best to remove it before it decides to drop on its own.
If you need a proper oak tree fertilizer, we wrote a guide on the best fertilizers for your oak tree!
Ash Tree Roots Cause Foundation Damage
Ash trees are often confused with some of our other problem trees like poplars, hickory, and boxelder.
The biggest problem with ash tree roots is that they are shallow. After the deep taproot is established, lateral roots form, both large and small. The ash tree’s large roots can equally be found in the A horizon of the soil (surface soil) as well as the B horizon (subsoil) according to the USDA Forest Service.
To identify an ash tree, check out the twigs! They will be opposite each other on the limbs instead of alternating like most other deciduous trees.
Poplar Trees Damage Foundations
The third most damaging tree on our list is poplar trees. These are often confused with quaking aspen trees or birch trees.
Poplar tree roots are typically a mix of shallow and deep roots. They don’t do well in compacted soil such as from construction in urban and suburban areas. Instead, they’ll find small pockets of loose soil to grow their roots.
This makes older foundations especially susceptible to poplar tree roots. If you have a small crack or imperfection in your foundation, a poplar tree root will find it and move in, widening the crack.
Norway & Silver Maple Tree Roots Damage Foundation
Unlike oak, ash, and poplar tree, not all maple trees are bad for your foundation. The two that are of most concern are Norway and silver maples.
Both Norway and silver maples are fast growers. Norway maple’s root systems are so shallow they can compete with your lawn grass for nutrients! Silver maples are known for their massive and fast-growing root systems.
If you plant a silver maple, it’s recommended to plant it at least 10 feet from your foundation. More, if you’re able.
The Norway maple is one of the only trees known to actually lift foundation instead of damaging it via shrinking of clay soils.
If you need a good maple tree fertilizer, take a look at our guide on the best fertilizers for maple trees here!
Black Locust Trees Grow Fast & Roots Can Damage Your Foundation
Robinia pseudoacacia, the black locust, is a fast-growing tree native to the Eastern U.S. This tree is very hard to control once it’s established, which makes it a possible problem tree for homeowners.
Black locusts reproduce in a similar way to aspen trees by creating clones. This is done through a process called suckering, where new shoots form from dying roots or old stumps.
Besides the difficulty of controlling these advantageous trees, they also have a very wide, fibrous root system. This can be problematic for foundations, especially because the roots are fast-growing.
In fact, it’s better if you just don’t even look at a black locust tree…
Boxelder Trees Can Lift Your Foundation
Boxelder trees are not very desirable in yards, streets, or urban areas. They attract boxelder bugs, are short-lived, and have brittle wood prone to dropping.
However, according to the US Forest Service, they can grow in a wide variety of conditions and pop up here and there on their own in many areas.
Similar to Norway maples, boxelder trees have a very shallow root system that can lift sidewalks and foundations, rather than shrinking the soil and causing settling.
Not ideal to plant near your home.
Spruce Tree Roots Can Damage Your Foundation
Two types of spruce trees can cause foundation damage. Brewer’s weeping spruce and the Norway spruce. Seems like Norway species are just a no-go all around, right?
According to a 2003 study, the roots of the Norway spruce prefer humus-rich soils, which are typically found near the surface in the O horizon.
While brewer’s weeping spruce do not have roots as shallow as the Norway spruce, they still cling to surface soils, with a few vertical roots penetrating deeper to hold the tree in place.
In total, the deeper the roots go (and the wider,) the more likely you are to have problems.
Other Trees That Damage Foundation
While the list of potentially damaging trees is long, the above-mentioned trees are the most likely to damage your foundation.
Here 8 other trees that can damage your foundation:
- Loblolly Pine
- Crimean Pine
These trees are not as likely to damage your foundation but have the potential due to their fast-growing and shallow roots.
How Do You Know If Tree Roots Are Damaging The Foundation?
It’s not unheard of for foundations to crack due to things other than tree roots. Soils naturally grow and shrink with weather conditions, buildings settle into the recently-dug soils, and even small tremors and earthquakes can cause damage, even if you can’t feel them.
Nonetheless, if you’re noticing small cracks around your foundation, you’ll want to learn what’s causing it as quickly as possible to avoid costly damage.
There’s really only one way to tell if tree roots are damaging your foundation, and that’s to physically look beneath the soil near your foundation and check for roots.
According to the University of Florida, you can do this by excavating the area around your foundation and looking for roots. This can be made easy if you draw a line from the nearest tree to your house and simply dig around this area of your foundation.
Don’t be fooled if you find no roots in the direct line from the tree. Roots can be far-reaching, so excavate a few feet in each direction to ensure you are seeing the whole scope of the root system.
How To Fix Damaged Foundation From Trees
Owning a home can be a wonderful experience. You get your own space, no need to worry about paying landlords or dealing with flimsy, thin walls between you and your neighbor.
But it’s a lot of work!
The last thing you want to deal with is damage to the very foundation of your home. Literally! Cracks and fissures in your foundation and sidewalk can be a headache, but there are ways to fix and prevent the damage from tree roots.
Water Your Foundation
Don’t worry, you read that right! It may sound strange, but watering the area around your foundation can fix your problem fast.
This typically works best if your foundation is built on clay soils. Trees tend to be stingy with their water, sucking in all they can get and leaving little for anything else around them.
When roots horde water, it causes clay soils to dry up, shrivel, and shrink. Watering the area around your foundation will inflate the soil back up, possibly closing the cracks on their own.
Even if your foundation damage isn’t caused by stingy tree roots, you can use this method to fix your foundation.
Plant Less Invasive Species
This solution doesn’t really work if there are invasive trees already in your yard. Unless you want to spend the money cutting them down and planting new trees, you may be stuck with your current landscape trees.
However, if you’re thinking of planting new trees or have just built a home and have the option to choose your landscape trees, pick tree species that are less harmful to the foundation.
Trees that are not prone to building damage include:
- Cypress Trees: There are several different types of cypress trees, but most have a deep taproot that is accompanied by lateral roots. These roots do not generally break the surface or cause problems in building foundations.
- Fruit Trees: Trees from the genus Prunus are pretty safe to plant around homes. These include plum, cherry, peach, apricot, and almond trees.
- Pine Trees: Except for Crimean, loblolly, and swiss tone pine, pine trees are an excellent choice to plant in your yard. Their roots tend to grow down instead of out, keeping your foundation safe from pesky roots.
Use A Tree Root Barrier To Save Your Foundation
Root barriers are meant to guide roots in a particular direction such as away from your foundation. They work by creating an impenetrable barrier that the roots cannot poke through, and must go around.
Something like DeepRoot Tree Root Barrier can help guide destructive roots away from your foundation, paved driveway, or sidewalks. The great thing about the DeepRoot product is it comes in a variety of sizes, so you can choose what best suits your situation.
Root barriers are especially effective on shallow root systems, which is what most of the damaging trees have. You can even use these on non-damaging roots such as bushes planted close to the house.
Getting To The Root Of The Problem!
Trees can add a lot of value to your landscape and they provide shelter, food, and shade to plenty of little critters that can be fun to watch. But one thing we don’t want our trees to do is harm our homes.
For trees like oak trees, they live for quite some time. Oak trees generally have a long lifespan. So, these foundation problems will only continue to grow!
If you notice cracks or fissures in your foundation, roots are not always the culprit. Be sure to check out what kind of trees are around your home to figure out if you have one of the more damaging trees around.
To recap, the trees most likely to damage your foundation include:
- Silver Maple
- Norway Maple
- Black Locust
- Norway Spruce
- Brewer’s Weeping Spruce
There are a host of other potentially damaging trees, but these 9 seem to be the most often talked about and the most destructive.
Trees with shallow roots that are less far-reaching come with their own problems. These trees tend to be susceptible to wind damage and can blow over more easily than trees that have deep taproots and far-reaching lateral roots.
Taking steps to prevent roots from reaching your foundation before you have a problem is the best approach to dealing with invasive roots. But all in all, trees tend to have a more positive impact on our yards than negative, especially if you’re aware of and prepared for wandering roots.
Biddle, G. (2001, October 10-13). Tree Root Damage to Buildings [Shallow Foundation and Soil Properties Committee Sessions at ASCE Civil Engineering Conference]. Houston, Texas. https://ascelibrary.org/doi/abs/10.1061/40592(270)1
Hitchmough, J., & Fieldhouse, K. (2008). Plant User Handbook: A Guide to Effective Specifying. John Wiley & Sons.
Randrup, T. B., McPherson, E. G., & Costello, L. R. (2001, March). Tree Root Intrusion in Sewer Systems: Review of Extent and Costs. Journal of Infrastructure Systems, 7(1). https://ascelibrary.org/doi/abs/10.1061/(ASCE)1076-0342(2001)7:1(26)
Roberts, J., Jackson, N., & Smith, M. (2006). Tree Roots in the Built Environment. The Stationery Office.