A neighbor's tree roots are damaging my fence, driveway or foundation. What can I do?

What is actually happening

Tree roots grow where water and oxygen are, which in Bay Area yards means the top 18 to 24 inches of soil and often straight under a fence line, patio or driveway. A root that was pencil-thin when the fence was built thickens every year, and a 6-inch root under a footing will lift it. Lifted or leaning fences, cracked slabs and heaved pavers are the usual symptoms.

Two things are often wrong about the complaint, which is why the facts need checking before the argument. First, the roots may belong to a different tree than the one being blamed, including the complainant's own. Second, the damage may have another cause: expansive clay, a drainage problem, a footing that was never deep enough. A root traced by excavation and photographed is evidence; a root assumed from the location of the trunk is not.

What California law says

• Ownership. Civil Code 833: a tree whose trunk stands wholly on one owner's land belongs to that owner even if its roots or branches extend onto another's land. Civil Code 834: a tree whose trunk stands partly on the land of two or more owners belongs to them in common. More →
• Self-help. You may trim roots and branches at the property line at your own expense, but Booska v. Patel (1994) 24 Cal.App.4th 1786 held that the right is not absolute: the neighbor who cut a Monterey pine's roots on his side owed a duty to act reasonably, and could be liable for the resulting harm to the tree. More →
• Nuisance. Civil Code 3479 defines a nuisance to include anything injurious to health or an obstruction to the free use of property. Encroaching roots that cause damage have been treated as a private nuisance supporting damages and abatement; roots that merely exist on your side generally have not.
• Fences. Civil Code 841 presumes adjoining owners share equal responsibility for a boundary fence, rebuttable by showing the presumption is unjust on the facts, with 30 days' written notice before work. Damage caused by one owner's tree is a common rebuttal.
• Small claims. Damage claims up to $12,500 for an individual go to small claims court (Code of Civil Procedure 116.221); the report is the evidence.

What your city adds

Almost every Bay Area city protects trees above a trunk size threshold, and many protect specific species regardless of size. That means nobody, including the owner, can remove the tree without a permit, and a fence problem is not usually grounds for one. Significant root cutting may also be regulated as "major pruning" or "damage" to a protected tree. Which rules apply depends on the city; Urban Forestry Guide's permit pages cover 56 jurisdictions, and the report cites yours.

What the report does for you

1. Identifies the tree and its owner frame: trunk position measured and photographed against the apparent line.
2. Traces the roots. Where we can excavate on your side, we expose and photograph the roots at the damage, identify them to the tree, and measure them.
3. States whether the roots are plausibly the cause, and whether another cause is more likely.
4. Says which roots can be cut without injuring the tree, and which cannot, with distances from the trunk for this tree.
5. Cites the Civil Code sections and your city's ordinance.
6. Recommends a fix: typically a root barrier, a relocated or redesigned footing, directed root pruning, or a cost-sharing proposal, with the hand-offs to a fence contractor or engineer named.

Dispute Assessment Report, from $850. Neighbor letter on letterhead, $150 add-on. Pricing and scope →

What to do this week

1. Photograph the damage and the tree with something for scale, dated.
2. Do not cut anything yet. Cutting first and asking later is how a fence dispute becomes a dead-tree lawsuit.
3. Talk to the neighbor once, in person or in writing, and keep a copy. Mediation and the view ordinances both expect it, and most people respond better before a letterhead arrives.
4. Get the facts in writing. Start a report, or text photos to (415) 881-0124 for a free read on whether a report will help.

Sources

1. California Civil Code § 833 and § 834, trees on and near boundaries.
2. California Civil Code § 841, adjoining owners' fence responsibilities.
3. California Civil Code § 3479, nuisance defined.
4. Booska v. Patel (1994) 24 Cal.App.4th 1786, First District Court of Appeal.
5. Code of Civil Procedure § 116.221, small claims jurisdiction.