Can tree roots damage building foundations?
Written by
Julia Anderson
Reviewed by
Prof. Charles Hartman, Ph.D.Tree roots generally do not affect a sound foundation, but take advantage of cracks or other defects in a foundation, which gives them access to moisture. When trees are planted too close to a building, their roots may become detrimental. The trees with exposed, spreading roots are also a source of danger if planted near structures, especially in clay soils, which shrink in dry seasons.
Soil Conditions
- Clay soils shrink during drought creating gaps roots exploit
- Sandy soils allow deeper root penetration away from structures
- Poor drainage attracts roots to foundation moisture
Tree Characteristics
- Fast-growing species like willows seek moisture aggressively
- Mature tree size determines root spread distance
- Surface rooters pose greater risks than deep-rooted trees
Roots cause damage based on moisture competition rather than physical force. In clay soils, trees take up the quantity of water that would keep the volume of the soil near the foundation, by which means they create voids in which settlement cracks are formed. There is but slight danger of the concrete breaking, unless it is continuous, because of root pressure alone.
Preventative measures include proper planting distances. Keep high-risk trees at least 15 meters from buildings and install root barriers if planting trees near a building that currently exists. Monitoring soil moisture levels during droughts can help maintain consistent conditions around the foundation.
The type of foundation is essential. Older foundations with cracks are susceptible to root intrusion. Modern poured concrete foundations that have proper footings are less likely to have roots penetrate. Regular inspections can catch early warning signs of cracks or soil separation at the foundation wall that may invite roots.
Remediation requires skilled assessment. Certified arborists determine whether roots are causing damage or exacerbating existing problems. Ranges of remedial processes vary from root pruning to foundation repairs. Under no circumstances should large roots be moved without the guidance of a qualified technician, as this may cause unstable trees.
Read the full article: 7 Essential Facts About Tree Root Systems
