· by Michael Blair, Nashville's Tree Service
Tree roots get blamed for foundation damage they rarely cause directly. In Middle Tennessee the actual mechanism is moisture: a large tree removes a great deal of water from clay soil, and clay that dries shrinks.
The moisture mechanism
A mature tree can transpire hundreds of gallons a day in summer. Drawing that from clay beside a foundation causes localized shrinkage and settlement on that side.
Removing a large tree can cause the opposite — the clay rehydrates over following seasons and heaves. Both are gradual and easy to attribute elsewhere.
Do tree roots damage sewer lines?
This is where roots genuinely cause damage. Clay tile laterals, common in pre-1970 Nashville housing, have joints every few feet, and roots enter at those joints seeking water.
Roots do not break into sound PVC. A house with a modern lateral and recurring blockages has a different problem.
- Roots rarely crack sound concrete directly
- Moisture extraction from clay is the real foundation mechanism
- Clay tile sewer laterals are genuinely vulnerable to roots
- Removing a mature tree can cause heave
- Root barriers work if installed correctly and deep enough
Planting distance
A common guideline is planting large species at least as far from the house as their expected mature height, and small ornamentals considerably closer.
It is not always achievable on a Nashville lot, which is where species choice matters more — smaller trees with less aggressive root systems near structures.
Should a tree near the house be removed?
Get an arborist assessment rather than removing on suspicion. A mature shade tree is worth a great deal in comfort, cooling cost and property value, and removal is irreversible.
If a root is genuinely lifting a walkway or entering a lateral, targeted root pruning or a barrier is often possible without losing the tree.
FAQ
Tree Roots, Foundations and Sewer Lines — questions
Can tree roots crack my foundation?
Directly, rarely — roots follow existing voids rather than exerting enough force to break sound concrete. Indirectly, yes: a large tree removes substantial moisture from clay soil, and shrinking clay withdraws support from a footing. In Middle Tennessee that indirect route is the one that matters.
How close can I plant a tree to the house?
A common rule is to keep large species at least as far away as their mature height, with small ornamental trees planted much closer without concern. On a typical Nashville lot that is often impractical for large species, which makes choosing a smaller tree the better answer than planting a large one too close.
Will removing a tree stop roots in my sewer line?
It stops new growth from that tree, but existing roots in the pipe remain and must be cleared, and neighboring trees may take advantage of the same joints. The durable fix is repairing or lining the lateral, since roots enter at failed joints rather than through sound pipe.
Can removing a tree cause foundation problems?
It can. A large tree draws a great deal of water from the clay around it, and once it is gone the clay takes that moisture back over the following seasons and swells, which can heave a foundation. The change is slow and easy to blame on something else, so have an arborist assess the tree before it comes down.