Your neighbor damaged your property. Here is how to get it paid for.

RPAPL § 861

Three legal theories, in plain English.

Almost every neighbor damage claim in New York rests on one of three ideas, and it helps to know which one you are standing on.

Negligence. Your neighbor had a duty to act with reasonable care, did not, and the carelessness damaged your property. The upstairs neighbor who ignored a running toilet for a week. The homeowner whose contractor dug too close to your foundation. The owner who knew a dead tree was leaning over your garage and did nothing. You prove what they should have done, that they did not do it, and what it cost you.

Private nuisance. Your neighbor's use of their property substantially and unreasonably interferes with your use of yours. Repeated flooding from a regraded yard. Constant vibration from equipment. Nuisance is about an ongoing condition rather than a single accident, and the remedy can include stopping it, not just paying for it.

Trespass. Something of theirs physically entered your property without permission. A contractor's crew that walked onto your lot and removed a fence. Water deliberately directed onto your land. A neighbor who cut a tree that was on your side of the line. Trespass does not require proof of carelessness; the entry itself is the wrong.

In practice, a demand letter pleads all three where the facts support them. The neighbor's insurer does not much care which label applies; it cares whether its insured is liable and for how much.

Situation one: water from above.

In apartments, the dominant neighbor claim is the leak. A bathtub overflows, a washing machine hose fails, a radiator valve is left open, and the unit below takes the water. The questions are who caused it, who was responsible for the fixture that failed, and whose insurance responds. In a co-op or condo the building's governing documents assign responsibility for pipes, fixtures, and finishes between the unit owner and the building, and the answer is often that the neighbor is responsible for the fixture, the building is responsible for the pipe in the wall, and you are responsible for your own floors until someone else is proven at fault. In a rental, the landlord is often the right target for the repair to your apartment, and the neighbor for your damaged belongings. All of that is on upstairs neighbor leak damage.

Situation two: construction next door.

A neighbor's renovation, extension, or new build can crack your walls, shift your foundation, flood your basement from altered drainage, or drop debris on your roof. The targets are the neighboring owner, who is generally responsible for work done on their land, and the contractor, who is responsible for doing it carelessly. In New York City, the Department of Buildings complaint process creates a record and can stop the work, but it does not pay for your cracks. The letter does that, and it usually goes to the owner, the contractor, and both of their insurers at once. Details on construction next door damaged my home.

Situation three: trees.

New York has a specific statute for trees. Real Property Actions and Proceedings Law § 861 makes a person who cuts, removes, or injures trees on someone else's land without permission liable for treble damages, measured against the value of the trees or the cost of restoring the land, as the statute provides, with a floor per tree. It also allows the landowner to recover the cost of restoration in addition to the multiplied figure in appropriate cases. The statute has a good-faith defense for someone who reasonably believed the land was theirs, which is why surveys matter. The neighbor who hires a crew to "clean up the line" and takes down three of your maples is looking at a very different number than the cost of three trees. Everything about that, including boundary trees and the rule for overhanging branches, is on neighbor cut my tree.

Two situations that look like neighbor damage but are not: a tree that fell in a storm with no warning, which is generally nobody's fault and goes to your own insurer; and damage done by a utility or the city on an easement or the public way, which is a claim against that entity under different rules and deadlines. If your case is one of those, the letter goes somewhere else.

Finally, keep the question of fault separate from the question of who pays. A neighbor can be entirely at fault and still be the wrong first target if the building or a contractor is the one with the insurance. The letter is usually addressed to all of them for exactly that reason.

Document it before you talk about it.

Neighbor disputes are lost in the first week, when people argue instead of documenting. Do these before the conversation:

• Photograph and video everything, with timestamps, including the source of the damage if you can see it (the neighbor's open hose, the excavation, the stumps).
• Get the cause in writing. A plumber's invoice that says "water intrusion from unit above, failed supply line," an engineer's letter attributing the cracks to adjacent excavation, an arborist's report on the trees.
• Get repair estimates, two if the number is large. Keep receipts for anything you had to do immediately (water extraction, tarping, emergency shoring).
• Report to the building if you are in one. The super's log and the management company's incident report are third-party records of what happened and when.
• Keep every message with the neighbor. "So sorry, my tub overflowed, I'll cover it" is an admission you will quote.

The insurance angle most people miss.

Your neighbor almost certainly has a homeowner's, co-op, condo, or renter's policy with liability coverage. That coverage exists to pay exactly this kind of claim, and it is usually far larger than what your neighbor would pay out of pocket. The neighbor may not want to report it. Your letter makes sure they do, by putting them on formal notice of a liability claim, which most policies require the insured to pass along to the carrier. Once the carrier has it, you are negotiating with an adjuster who handles these every day and settles most of them.

Your own policy may also respond, particularly for water damage to your contents. Claiming on your own policy is sometimes the fastest route to getting paid, after which your insurer pursues the neighbor's insurer for reimbursement. The cost is your deductible and, possibly, your premium. A letter to the neighbor does not prevent you from doing this; it often runs alongside it.

What a demand letter does here.

In a neighbor case the letter has one job above all others: get the claim in front of the neighbor's insurer, with a number and the evidence attached, in a form the adjuster can act on. It identifies the event, the cause, the legal basis (negligence, nuisance, trespass, and the tree statute where it applies), the damages with estimates and receipts, and a deadline. It tells the neighbor to forward it to their carrier. It preserves the claim against the contractor or building where one of them shares fault. And it does all this without you having to raise your voice across a fence.

A second job is to stop the damage where it is continuing. A leak that is still leaking or an excavation that is still running gets a demand to cease as well as a demand to pay. That sets up an injunction if one is needed and documents that the neighbor was told.

Our neighbor letters go to every party that might be responsible, with a request that each tender the claim to its insurer. See how our flat-fee demand letters work.

A worked example.

A Park Slope homeowner discovers a long diagonal crack across the party-wall side of her living room the week her neighbor's contractor finishes excavating for a rear extension. She photographs it daily as it widens, files a DOB complaint, and hires an engineer who attributes it to inadequate underpinning next door. The repair estimate is $18,500.

The letter goes to the neighbor, the contractor, and the neighbor's insurer, with the engineer's report, the photographs, and the estimate. It asserts negligence and trespass, notes the DOB complaint, demands $18,500 and a structural inspection at the neighbor's expense, and sets a deadline. The contractor's liability carrier, which has handled this claim a hundred times, opens a file and sends its own engineer. The case settles for the repair cost plus the engineer's fee without a lawsuit. Had it not, the claim is above small claims limits and goes to civil or Supreme Court, where the letter and the engineer's report are the first two exhibits.

Small claims, and when to skip the letter.

Smaller neighbor claims fit small claims well: up to $10,000 in New York City, generally $5,000 in city courts elsewhere, and $3,000 in town and village courts. You do not need a lawyer, and the bench hears leak and fence cases constantly. Our New York small claims court guide covers the filing, and demand letter vs. small claims covers the sequencing. A judgment against a homeowner is generally collectible, because they own a home.

When is a letter the wrong tool? When the damage is trivial and a conversation will fix it. When you caused part of it yourself and the letter would invite a counterclaim. When the real fight is with your own building or landlord rather than the neighbor, in which case start at landlord won't make repairs. And when a tree dispute has escalated beyond money into an injunction fight over a boundary, where a survey and litigation counsel come before any letter.

Read next.

• Upstairs neighbor leak damage: co-ops, condos, and rentals; who is responsible for what.
• Neighbor cut my tree: treble damages under RPAPL § 861, boundary trees, and overhanging branches.
• Construction next door damaged my home: cracks, vibration, excavation, and DOB.
• Uninsured driver hit my car: the same negligence claim, on the road.