Trees, Roots & Your Foundation

As a homeowner, have you ever noticed one of the following scenarios happening to your house?

  • Your house seems to slope towards trees or bushes
  • Your house has foundation damage near shrubs, bushes or trees
  • You have damage on the side of the house that receives the most sunshine

If you answered “Yes” to any of these questions, your house may be in need of foundation repair and an assessment from an independent engineer. Before considering the worst-case scenario it’s important to:

  1. Understand the potential causes of the foundation issues
  2. Gain an understanding of which trees are more likely to cause damage
  3. Learn how to prevent or repair your home’s foundation

Tree Impact: Potential Causes of Foundation Issues

A large tree located on the side of your house may cause your home foundation to settle. That side may settle due to moisture loss while the other sides of the house do not. This will cause the soil in this area to shrink (due to moisture loss) and separate from the bottom of the foundation. This area of shrinkage creates a void. When the voided area becomes too large, the concrete foundation will collapse to find its support, causing one or more cracks in the home foundation.

This is of particular concern to homeowners in the Dallas Metroplex area because of the presence of shallow fat clays that attract water molecules on a molecular level. This attraction causes the clays to expand when they take on this additional volume of moisture. When the clay dries out, it shrinks because of the loss of voluminous water molecules.

Understanding Trees on Your Property

To give you a sense of how much water trees can use, it’s important to consider the following:

Some trees use 15 gallons of water per hour on a hot day and some can draw as much as 200 gallons of water. Large oak trees are an example of a tree that can draw up to 50 gallons of water each day.

Below are examples of some common trees and their levels of water demand.

High Demand Trees

  • Elm
  • Oak
  • Poplar
  • Willow
  • Silver Maple
  • Manitoba Maple

Moderate Demand Trees

  • Cherry
  • Ash
  • Hawthorn
  • Hornbeam
  • Other maples (Sugar, Red)
  • Mountain Ash

Low Demand Trees

  • Beech
  • Birch
  • Mulberry
  • Cedar
  • Fir Pine
  • Spruce

How to Prevent or Repair Your Home Foundation

Below are a few things that you, and if needed, an independent engineer can do to help prevent or repair foundation damage.

  1. Preventative Landscaping
  • Don’t plant trees or shrubs near your foundation
  • If it’s too late, see below for how to address this issue
  1. Use Foundation Maintenance Soaker Hoses
  • Help protect against evaporation by sealing the top layer of clay
  • Keeps the soils relatively moist and helps feed the roots so they do not grow under the center of the home (interior settlement is highly undesirable)
  • Very important to utilize year round
  1. Use Root Barricades
  • Helps prevent tree root growth in areas where they are not desired. Root barriers aren’t foolproof but they help.
  • Root barricades are the easiest way to combat water withdrawal—especially for properties with large trees like oak, Arizona Ash and Chinese tallow, which all have high demand root systems that require large amounts of water from the soil.
  1. Tree and Bush Removal
  • Removal of bushes and trees may be the only course of action in extreme scenarios
  • Trees that are immediately adjacent to your home should be removed to avoid foundation issues
  • If the tree is 20 to 30 feet from the home, a root barrier can be installed about three to five feet from your foundation. This will prevent tree roots from removing moisture from the zone of influence around and below your foundation.

Which solution is best for you? Contact Crosstown Engineering today to speak with a licensed professional engineer.

Photo credit: Aaron Escobar