A neighbor's Coast live oak: what it does, what the law allows, and what the report settles

What the tree actually does

Coast live oaks are evergreen, long-lived (200 years and more) and shallow-rooted: most roots are in the top two feet of soil and spread well beyond the canopy. The large lateral roots within about 10 feet of the trunk are structural; cutting them destabilizes the tree. Limbs are heavy, often horizontal, and prone to failure when the tree has been over-irrigated, had fill placed over its roots, or been topped. Summer irrigation and lawn under an oak are the usual causes of root crown decay, which is the usual cause of whole-tree failure. Leaf drop is year-round and is not a sign of trouble.

The disputes it causes

Roots under fences, patios, pool decks and foundations on lots built around the tree; limbs over neighbors' roofs; sudden limb drop in late summer; a dying oak with root crown decay leaning at a house; and, everywhere, the neighbor who wants it gone and the city that will not allow it.

What the law says

• The trunk decides ownership (Civil Code 833 and 834).
• You may trim branches and roots that cross onto your land, reasonably and without injuring the tree (Booska v. Patel).
• Roots or limbs causing actual damage can be a nuisance; shade, litter and a blocked view are not (Civil Code 3479).
• A hazardous tree the owner knows or should know about is the owner's liability when it fails; written notice with an arborist's findings establishes that (Civil Code 1714). See dead or leaning tree next door.
• Cutting a neighbor's tree past the line, or injuring it, carries double or treble damages (Civil Code 3346).

What the city adds for this species

Protected at 4 inches DBH in Oakland and Sausalito, 11.5 inches in Palo Alto, 18 inches circumference in Berkeley (the only private species Berkeley regulates), and at small sizes in Atherton, Woodside, Portola Valley, Menlo Park, Los Altos Hills, Saratoga, Los Gatos and most of Marin and Lamorinda. Oakland's and several Marin view ordinances exempt coast live oak from view remedies entirely. Removal for a neighbor's convenience does not get a permit anywhere; removal for a documented hazard does. Rules by city →

What the report settles

Which roots at the fence or slab are structural and which can be pruned; a root barrier placement that will not harm the tree; whether the limbs over the roof can be reduced without topping; whether root crown decay is present and what the target is; and the city tier the tree falls in. Oak disputes are specification disputes.

Dispute Assessment Report, from $850. Start the report or text (415) 881-0124 with a photo for a free read.