Plan ahead
Tree roots are damaging my property
Tree roots commonly lift sidewalks and driveways and enter sewer lines that already have cracks or loose joints. They rarely break a sound foundation directly, but in shrink-swell clay soils large trees can dry the soil and add to foundation movement. Options include root pruning, root barriers, pipe repair and redesigning hardscape. Removal is a last resort, and cutting big roots can make a tree unstable.
What to do and what not to do
What to do
- Identify the tree and measure how far it is from the damage.
- For sewer backups, have a plumber camera-inspect the line to confirm roots and the cause.
- For foundations, get a structural engineer's opinion before blaming the tree.
- Check who owns the tree. Street trees are often the city's.
What not to do
- Don't cut large roots close to the trunk. It can destabilize the tree.
- Don't pour chemical root killers into the ground near trees you want to keep.
- Don't remove a large tree near a clay-soil foundation without advice; it can change soil moisture.
Options short of removal
- Root pruning with a clean cut at a safe distance from the trunk, done by an arborist
- Root barriers installed along sidewalks, slabs or pipe runs
- Repairing or relining sewer pipes so roots have no entry point
- Rerouting or rebuilding paths with flexible materials or bridging over roots
Roots vs. foundations, pipes and pavement
Cutting large roots close to the trunk can destabilize a tree and make it a fall hazard, so root pruning near a mature tree should be planned with an arborist, not done during a sidewalk repair on the fly.
Sidewalks and driveways
- What roots actually do
- Lift thin slabs as they thicken near the surface
- What usually helps
- Root pruning during repair, a root barrier, or flexible paving
Sewer and drain lines
- What roots actually do
- Enter pipes through existing cracks and joints, then block them
- What usually helps
- Repair or line the pipe; removing the tree alone doesn't fix the crack
Slab foundations in clay soil
- What roots actually do
- Draw moisture from shrink-swell clay in droughts, adding to movement
- What usually helps
- Consistent soil moisture, a foundation engineer's assessment
Basement walls
- What roots actually do
- Rarely break sound walls; follow existing cracks
- What usually helps
- Fix the wall and drainage first
Common questions
Can tree roots crack a foundation?
Rarely directly. Most foundation cracks come from soil movement. In expansive clay, though, large trees drawing moisture can contribute. A structural engineer can tell you whether the tree is a factor.
Will grinding the stump stop root problems?
Once a tree is removed, its roots stop growing and slowly decay. Grinding removes the stump and top roots; deeper roots are left to rot.
Will removing a tree stop roots from damaging my foundation?
Not always. In shrink-swell clay, removing a large tree can let the soil swell as it rewets, which also moves a foundation. Have a foundation professional evaluate before removing a big tree for foundation reasons.
