The job next door is cracking your walls.

Negligence · Trespass · NYC Building Code (Adjoining Property Protection)

What construction does to the house next door.

The damage usually shows up in one of four ways. Cracks in plaster, drywall, and masonry, especially diagonal cracks above doors and windows and step cracks in brick, which indicate the building moved. Doors and windows that suddenly stick. Water in a basement that was dry, because the neighbor's excavation changed how groundwater moves or the new foundation redirected runoff. And, in the worst cases, visible settlement: a floor that slopes, a party wall that bows, a gap opening between your building and theirs.

The causes are excavation that undermines your foundation, vibration from demolition, pile driving, or heavy equipment, removal of lateral support when the neighbor digs below your footing, and careless water management. New York City's construction code requires a person doing excavation or construction to protect adjoining property, and where the work goes below a certain depth the obligation to underpin or otherwise protect the neighbor's foundation falls on the party doing the work. The details are technical and we describe them in words deliberately; the point is that the burden of protecting your house during their project is generally theirs, not yours.

Who is responsible: the owner and the contractor.

There are two primary targets, and the letter goes to both.

The neighboring owner. The owner commissioned the work and benefits from it. In New York, an owner who undertakes excavation or construction that damages an adjoining building is generally responsible for the damage, and the owner cannot entirely escape that by pointing at the contractor. The owner's property insurance and, for larger projects, a project-specific liability policy respond to the claim.

The contractor. The general contractor and any excavation or demolition subcontractor are responsible for doing the work carelessly. They carry commercial general liability insurance, and on permitted work in New York City they were required to have it in force. The contractor's carrier is often the one that actually pays.

There may be a third: the engineer or architect of record whose design or monitoring was inadequate. That is a professional negligence claim and usually comes later, if at all. And the building itself, if you are in a co-op or condo, has its own claim for the structure, while you have one for your unit; coordinate with the board.

Licensing and permits: the record that already exists.

New York City requires permits for most construction and licensing for the trades doing it. The Department of Buildings' online records show the permit, the owner, the contractor, the contractor's license and insurance status, and any complaints and violations on the job. Pull all of it before you write a letter. A contractor working without a permit, or outside the scope of the one issued, has a problem that becomes your leverage. A contractor whose insurance lapsed mid-job has a bigger one, for both of you.

Outside the city, the local building department holds the permit file. The same questions apply: was the work permitted, who is the licensed contractor, and what did the permit application say about protecting adjoining property?

The DOB complaint: what it does and does not do.

In New York City, a complaint to the Department of Buildings through 311 about damage from adjacent construction triggers an inspection. If the inspector finds the work is endangering your property or proceeding without adequate protection, the DOB can issue violations and a stop-work order. That matters enormously if the damage is ongoing: it stops the excavation while the underpinning gets fixed, and it creates an official record that the condition existed on a given date.

What the DOB will not do is pay for your cracks, order the neighbor to pay, or resolve who is at fault as between you and them. The complaint is a tool for stopping the damage and building the record. The money comes from the demand and, if needed, the lawsuit. File the complaint the day you see the first crack, then start documenting for the claim.

Pre-construction surveys, and what to do if you never got one.

On a serious project in New York City, the neighbor's engineer should have asked to inspect your building before work began and to prepare a pre-construction survey documenting its condition. That survey is supposed to protect both sides: it shows which cracks were already there. If you were asked and you refused, expect the other side to argue that every crack pre-existed. If you were never asked, that is a point in your favor, because it suggests the required protection plan was not followed.

If work is starting next door and has not yet damaged anything, say yes to the survey, attend it, and take your own photographs of every wall, ceiling, and foundation surface the same day. Ask for the vibration monitoring plan and whether crack monitors will be installed. Get the name of the contractor's insurer now. This costs you an afternoon and it is the single best investment in the claim you hope never to make.

Document it like a case, because it is one.

• Dated photographs of every crack, with a ruler or coin for scale, repeated weekly while work continues. A crack that widens on camera is the most persuasive evidence there is.
• Your own engineer. A licensed structural engineer's report attributing the damage to the adjacent work is what converts your complaint into a claim the insurer cannot dismiss as "old house, old cracks."
• Repair estimates from a contractor who does structural work, not just a painter.
• The DOB file: the complaint, the inspection results, any violations and stop-work orders.
• Communications with the neighbor, the contractor, and the site super. Keep the text where the super said "yeah, we went a little deep."
• Cost of living elsewhere if the damage made any part of the home unusable.

What a demand letter does here.

Construction damage claims fail by drifting. The neighbor says talk to the contractor, the contractor says talk to the insurer, the insurer says it never received a claim. A demand letter ends the drift. It goes to the owner, the general contractor, and any identified subcontractor at once, with the engineer's report, the photographs, the DOB record, and the estimates attached. It asserts negligence, trespass where material physically crossed the line, and the owner's and contractor's obligations to protect adjoining property. It demands payment of the repair cost, an immediate halt to any work that is still causing damage, and access for your engineer to inspect their excavation. It requires each recipient to tender the claim to its carrier and to identify the carrier to you, and it sets a deadline with a filing date behind it.

Once the carriers are involved, the claim moves. Adjusters on construction liability policies expect exactly this package, and a claim that arrives with an engineer's report and a DOB violation attached is one they would rather reserve and settle than litigate. Our flat-fee demand letters page explains how we handle it. For the underlying legal theories, see the neighbor property damage hub.

A worked example.

A Bay Ridge rowhouse owner notices step cracks in his rear facade and a basement door that no longer closes, three weeks into the neighbor's cellar dig. He files a 311 complaint; the DOB finds inadequate underpinning and issues a partial stop-work order. His engineer attributes the settlement to the excavation and estimates $42,000 in structural repair and finishes.

The letter goes to the neighboring owner, the GC, and the excavation sub, with the engineer's report, the DOB record, weekly crack photographs, and the estimate. It demands the repair cost, a stabilization plan before work resumes, and the insurers' identities. The GC's carrier and the owner's project policy both open files. Their engineer inspects, the underpinning is corrected, and the claim settles for the repair figure plus the engineer's fees. The owner never files suit. Had he needed to, the amount is far above small claims limits and the case goes to Supreme Court, where the letter, the engineer's report, and the stop-work order anchor the complaint.

When a letter is not the tool, and when it is not enough.

Hairline cracks in old plaster with no movement, and no evidence connecting them to the work, are not a claim; save your money. If the damage is active and serious, a letter is the beginning, not the end: you may need an emergency court order to stop the work, and that is litigation counsel, today. If the contractor is unlicensed and uninsured and the owner is a shell entity, the letter still sets up the claim, but collection is the real problem; see collecting a judgment. Smaller claims fit the small claims courts; most construction damage does not. Neighbor tree damage during site clearing has its own statute, on neighbor cut my tree.