Legal Question in Real Estate Law in California

Re: Tree Roots

For now, you probably have the choice of trimming the roots or paying for the damage they do, in addition to just cutting it down. It's your tree, the roots constitute a trespass when they enter another's property, and you are responsible for the harm done.

If the roots go on to cause an aggravated kind of harm such as breaking foundations or clogging sewer pipes, they might become a private nuisance that would entitle the neighbor to get an order for you to abate the nuisance, which would likely involve removing the tree.

I suggest consulting an arborist for advice on whether the roots can be trimmed successfully, whether a subsurface barrier might prevent their repeated or further growth, and whether (and when) removal might be necessary.

If the trunk of the tree stood on the property line, it would be a jointly owned tree and therefore a shared cost, but if the trunk stands entirely on your land, it's your problem. I might add that the neighbor can resort to self-help by cutting the roots, but must do so in a way that does not unduly injure the tree nor make it a blow-over hazard.