Trees are a beautiful addition to any landscape, streetscape or property, but they can also pose a threat to the foundations of houses and other structures if not managed properly.
Tree Damage to Slabs and Footings: Why Does it Happen?
Trees can damage slabs or footings of houses when their roots grow underneath them and cause them to lift or crack. This can happen because of the following reasons:
- Foundation Type: Homes built on shallow foundations or on unstable soils are more likely to experience damage from tree roots.
- Soil Type: Trees planted in clay soils will cause more damage than trees planted in sandy soils.
- Tree Species: Some trees have more aggressive root systems and can cause more damage than others.
The roots of trees can grow to lengths of three times their height, and in some cases, even more. As they grow, they can damage anything that gets in their way, including underground pipes, sidewalks, and even foundations.
Physical Root Damage versus Matric Suction
Roots can cause two types of damage – physical root damage due to growth and expansion and matric suction. Physical root damage occurs when the roots push against the foundation or structure and cause it to crack or lift. This type of damage usually occurs with large, mature trees. Matric suction occurs when the roots extract water from the soil causing it to shrink and pull away from the foundation or structure. This type of damage usually occurs with younger, more immature trees.
Tree Species: Which Ones Are the Worst Offenders?
Some trees are more prone to causing damage than others. For example, trees with large, aggressive root systems like the willow, oak, and eucalyptus can cause significant damage to the foundation of a house. Some trees with less aggressive root systems can still cause damage, such as pine trees whose shallow roots can grow up into the slab of a house.
Is it the tree? Or the way the house was built?
It is important to determine whether the damage was caused by the tree or the way the house was built. A professional arborist can examine the tree and assess its root system to determine whether it is causing the damage. If the tree is causing the damage, a professional engineer can determine the extent of the damage and recommend the best course of action.
What Can Be Done Other Than Tree Removal?
If a tree is causing damage to the foundation or structure of a house, there are options other than tree removal. For example, a root barrier can be installed to prevent the roots from growing into the foundation or structure. In some cases, selective root pruning can be done to redirect the roots away from the foundation or structure. If the damage is severe, it may be necessary to remove the tree, but in many cases, other options are available.
Famous Examples of Trees That Have Caused Damage
There are many examples of trees that have caused significant damage to structures. For example, the Ficus trees in the Hollywood Hills in California have caused significant damage to sidewalks and other structures. The Ficus tree has an aggressive root system that grows quickly and can cause significant damage to foundations and structures.
Another example is the Fortingall Yew, which is one of the oldest trees in the world, located in Scotland. The tree is estimated to be between 2,000 and 5,000 years old and has caused damage to the church that sits beside it. The tree’s roots have grown into the churchyard and have caused significant damage to the church’s foundation, requiring extensive repairs.
In addition to these examples, there are many instances where trees have caused damage during storms or high winds. In 2017, Hurricane Irma caused widespread damage to trees in Florida, with many falling on homes and power lines, causing millions of dollars in damage. Similarly, in 2012, Hurricane Sandy caused significant damage to trees in New York City, with many falling onto cars, buildings, and other structures.
Preventing Root Damage
While trees can add value to a property and provide numerous benefits, they can also cause significant damage if not properly maintained or located. There are several steps that property owners can take to prevent tree damage, including:
- Regular tree maintenance: Regular maintenance can help identify and address potential tree issues before they become serious problems. This includes pruning branches and removing dead or diseased trees.
- Proper tree selection: Property owners should choose trees that are appropriate for their location and climate. Certain tree species, such as Ficus trees, have aggressive root systems that can cause damage to structures.
- Strategic placement: Property owners should consider the location of trees in relation to structures. Trees should be placed far enough away from buildings to prevent damage to roofs, gutters, and foundations.
- Structural reinforcement: Property owners can reinforce structures, such as decks and patios, to better withstand potential tree damage.
- Consult with a professional: Property owners should consult with a professional arborist or tree removal service to assess potential tree risks and develop a plan to mitigate damage.
While trees can provide numerous benefits, they can also cause significant damage to structures and properties if not properly maintained or located. Property owners should take steps to prevent tree damage, including regular maintenance, proper tree selection and placement, and consulting with professionals. By taking these steps, property owners can enjoy the many benefits of trees while minimizing the risk of damage to their structures and properties.
Ten interesting facts about trees and structural damage:
- Tree roots can grow up to three times the height of the tree and spread two to four times wider than the height of the tree.
- Trees with shallow root systems are more likely to cause structural damage than those with deep root systems.
- The type of soil and moisture levels can affect the likelihood of a tree causing structural damage.
- Trees that are regularly pruned and maintained are less likely to cause structural damage than those that are not.
- The age and size of a tree can also affect the likelihood of it causing structural damage.
- Trees can cause damage to both underground and aboveground structures.
- The type of tree species can affect the likelihood of it causing structural damage.
- Trees that are planted too close to structures are more likely to cause damage.
- The effects of structural damage caused by trees may not be immediately noticeable and can worsen over time.
- Regular tree inspections and maintenance can help prevent structural damage caused by trees.
Links to additional reading on this topic:
- “Tree Root Damage to Buildings” by the University of Illinois Extension: https://extension.illinois.edu/tree-root-damage-buildings
- “Structural Damage from Tree Roots” by the City of San Diego: https://www.sandiego.gov/sites/default/files/legacy/development-services/pdf/infobulletins/ib520.pdf
- “Trees and Structural Damage: What You Need to Know” by Davey Tree: https://www.davey.com/arborist-advice/articles/trees-and-structural-damage-what-you-need-to-know/
From the TreeFuture collection
Read about some other topics here:
Back to the TreeFuture main page
