Ensuring Trees and Buildings Live Well Together

Trees are generally a desirable feature of home and commercial landscaping, however they can pose a threat to buildings and other structures in a number of different ways.

Contrary to popular belief, tree roots cannot normally penetrate a building’s foundation. They can, however, cause damage by penetrating through pre-existing cracks. Large root systems that extend beneath a house can cause foundation uplift, and roots can leach water from the soil beneath foundations, causing the structures to settle and sink unevenly.

There are also other risks associated with the close proximity of trees and structures, and while less dramatic than foundation damage, can cause extensive damage in a more indirect manner, for example:

  • Trees that are too close to buildings may be fire hazards.
  • Leaves and broken branches can clog gutters, potentially causing water penetration.
  • Old, damaged or otherwise weak trees may fall and endanger lives and property.
  • Tree roots can potentially penetrate underground drainage pipes, especially when they leak. Water that leaks from a drainage or sanitary pipe can encourage root growth in the direction of the leak, where the roots may eventually enter the pipe and obstruct its flow.
  • Trees may be used by insects and rodents to gain access to the building.
  • Falling trees and branches can disrupt power and telephone lines.

For more information about the risk assessment of trees, click here.

Structural Defects in Trees

Trees with structural defects likely to cause failure to all or part of a tree and can damage nearby buildings. The following are some of the indications that a tree has a possible structural defect:

  • Dead twigs, dead branches, or small, off-color leaves
  • Some species often form weak branch unions, while some other fast-growing species may be prone to breakage or uprooting
  • Cankers, which are localized areas on branches or stems of a tree where the bark is sunken or missing
  • Hollowed trunks
  • Advanced decay (wood that is soft, punky or crumbly, or a cavity where the wood is missing) can create a serious hazard
  • Cracks can indicate a very dangerous condition as the tree may be in the process of failing
  • The tree leans at more than 15 degrees from vertical

Commissioning a tree report is the first step in assessing the structural integrity of trees. Read more about tree reports here.