The NYC Alteration Agreement, What It Is and What It Cover

An alteration agreement is a contract between you and your building. Before your contractor begins work, you and the board sign a document that defines what you are permitted to do, when the work can happen, who must be insured, how the building is protected, and what happens if the project causes damage or runs past its approved schedule.

The alteration agreement is the building's process for governing renovation work. It applies whether or not the renovation also requires permits from the Department of Buildings or approvals from other city agencies. For work that requires both, the two processes run in parallel. The city reviews work under public law. The building reviews work as the owner or governing body of the property where the work happens.

The agreement also does not replace asbestos filings, landmark approvals, trade permits, contractor licensing, or any other public approval the work may require. It sits alongside them.

What kind of document this is

The alteration agreement is a private contract between you and your building. It comes from the board and is shaped by the building's governing documents, physical systems, insurance requirements, house rules, and renovation history.

In a co-op, the legal authority to require one usually flows from the proprietary lease. When you buy into a co-op, you buy shares in a corporation and receive a proprietary lease that gives you the right to occupy the apartment. That lease typically gives the board authority over alterations, and the alteration agreement is how the board applies that authority to a specific project.

In a condo, the authority comes from the declaration and bylaws. As a condo owner, you own real property rather than shares in a corporation. That distinction affects how the agreement is structured, what the board can require, and who is protected by the indemnity provisions. Condo boards generally operate with less discretionary authority than co-op boards, but a signed alteration agreement still gives the board meaningful rights during the project.

The NYC Bar Association publishes model alteration agreement forms. Its co-op form was updated in 2010. Its condo form was approved in 2026 by both the NYC Bar Association and the New York State Bar Association. These forms are starting points that each building adapts to its own structure, systems, risk tolerance, and policies. The alteration agreement for a 1920s prewar building on the Upper West Side will look different from one for a 1970s postwar building in Rego Park. The plumbing lines may be organized differently. The mechanical systems may differ. The building may have different rules about wet areas, risers, noise, elevator use, working hours, and contractor access.

Co-op and condo agreements compared

What you submit before the agreement is signed

The alteration agreement does not appear out of nowhere. Before the board approves the work and provides the agreement for signature, it usually wants to see what you are planning.

A submission typically includes architect-stamped drawings for work affecting structure, plumbing, electrical systems, mechanical systems, sprinkler systems, fire alarm systems, or other building systems. It also includes a written scope of work, the contractor's license information, insurance certificates, and any building-specific forms the managing agent requires.

The first useful step is to request the building's alteration package before the design is far along. That package usually includes the alteration agreement, house rules, submission requirements, insurance requirements, contractor rules, working-hour limits, fee schedules, and contact instructions. It may also include building-specific restrictions, such as wet-over-dry rules, limits on floor penetrations, requirements for soundproofing, rules for shutoffs, or required consultants.

Getting those rules early can shape what is feasible to design. Knowing at the start that the building limits wet-area relocation, requires a structural engineer, or prohibits a certain mechanical system avoids a redesign after the board's reviewer raises objections later.

Most buildings send the drawings to a reviewing professional, usually a licensed architect or engineer retained by the building. This person reviews the plans from the building's perspective, looking at risk to the structure, risers, waterproofing, electrical capacity, mechanical systems, common areas, neighboring apartments, and future access to building infrastructure. You almost always pay their fee. A low-to-mid-thousands range is common for substantial projects, though the number depends on the building, the scope, and how many review rounds are needed. The agreement or alteration package controls the actual fee.

Review timelines vary. Some boards review monthly. Some managing agents collect packages and send them to the building's reviewer on a rolling basis. Some projects move in a few weeks. Others take six to eight weeks or longer, especially if the plans raise technical questions. Asking the managing agent about typical timing before you commit to a contractor's start date is a practical early step.

Construction rules and building access

The alteration agreement governs how construction happens, not just what the board approves.

Working hours are usually restricted. Weekday daytime hours are the standard, often around 9 a.m. to 5 p.m., though the exact window varies by building. Saturday work may be allowed, but it often requires advance notice and may be limited to quiet work or non-disruptive tasks. A project that looks like eight weeks on a contractor's schedule can stretch when building hours, elevator availability, holidays, and blackout dates are added.

Materials and debris usually move through the freight elevator. The freight elevator often has to be reserved with the superintendent or managing agent. Availability may be limited by moves, deliveries, maintenance work, other residents' projects, or building staffing. These constraints affect the construction schedule in practical ways. A demolition day can become two days if elevator access is limited. A delivery can be delayed if protection is not in place or if the building does not allow materials through the passenger elevator.

Common-area protection is the contractor's physical job, but it is your legal obligation. The agreement typically requires hallway floors to be covered, elevator cabs to be padded, walls and corners to be protected, and building entrances to be kept clear during active work. If the lobby, elevator, hallway, stair, or service area is damaged during your renovation, the cost of repair usually falls on you.

The building retains inspection and observation rights during the project. In a co-op, those rights are usually grounded in the proprietary lease and the alteration agreement. In a condo, they are usually grounded in the governing documents and the signed alteration agreement. The 2026 NYC Bar condo form gives the board's designated representatives access rights during construction, including inspection rights while the owner, the owner's representative, an occupant, or workers are present. The exact access process depends on the signed agreement.

Some buildings maintain approved contractor lists or require specific licensed professionals for certain trades. Others do not keep a formal list but still reserve the right to reject a contractor who does not satisfy the building's insurance, licensing, experience, or conduct requirements. Confirming that your contractor qualifies before signing a construction contract is the right sequence.

Insurance requirements

Insurance is where many projects run into unexpected delay. The requirements exist because the building needs assurance that the contractor's work is backed by coverage if something goes wrong.

The contractor usually must carry general liability insurance, workers' compensation insurance, disability benefits coverage where required, and in some buildings umbrella or excess liability coverage. The building, managing agent, board, and other parties listed in the agreement usually must be named as additional insureds on the contractor's policy.

Additional insured status gives those parties a direct path to the contractor's insurance for a covered claim arising from the work. If the contractor damages a riser, causes a leak, injures someone in a common area, or damages building property, the building can pursue the contractor's coverage directly.

General liability minimums vary by building. In practice, many buildings require limits around $1 million per occurrence and $2 million aggregate, though larger buildings, older buildings, and buildings with more complicated systems may require higher limits. Umbrella requirements also vary. The alteration agreement controls the actual numbers.

A contractor's standard insurance certificate often does not satisfy the building on the first submission. The policy may need specific endorsements, additional insured wording, waiver of subrogation language, completed-operations coverage, or other language the agreement requires. If asbestos-containing material is present or suspected, asbestos-related coverage or separate abatement documentation may also be required.

The NYC Bar model co-op agreement specifies several insurance endorsements explicitly. The model forms also require coverage to extend beyond the completion of work in certain respects, because construction-related damage can appear after the crew leaves. Water intrusion is the common example. A slow leak behind new finishes can take time to appear.

Insurance documentation is often the last outstanding item before a project can start. The contractor's broker may need several rounds to issue a certificate that the managing agent and building counsel will accept. That time should be built into the schedule.

Indemnification

The indemnification clause shifts financial risk from the building to you and your project team.

You agree to defend, indemnify, and hold harmless the building parties listed in the agreement from claims arising from the renovation work. In a co-op, those parties often include the corporation, managing agent, board members, employees, and other parties named in the agreement. In a condo, they often include the board of managers, condominium association, managing agent, unit owners, employees, and other listed parties.

The obligation is broad. It can cover personal injury claims, property damage claims, building damage, damage to neighboring units, liens, and legal costs. If a worker is injured during the project, if a pipe your contractor disturbed leaks into the apartment below, or if a materials delivery damages the lobby, the agreement directs the response and cost back to you and your project team, subject to the terms and carveouts in the signed agreement.

The obligation also runs downstream. You usually must require your contractor to sign a separate contractor's agreement with indemnification obligations running to the building. Subcontractors may need to do the same. The insurance requirements give those indemnification promises financial backing.

There is also a restoration provision that owners do not always anticipate. If the building later needs access to infrastructure behind your renovation, restoration of your finishes may be your responsibility. For example, if the building needs to repair a pipe behind a new wall, cabinet, or tiled surface, the building may be responsible for the pipe work while you are responsible for restoring your renovation afterward.

The NYC Bar model co-op agreement is explicit about this kind of owner responsibility, and the condo form includes parallel concepts for unit owners. Buildings need to maintain older infrastructure behind newer apartment finishes. The restoration provision is how the building handles access to building systems that an owner has enclosed or finished around, without generating a dispute each time.

Indemnification also differs structurally between co-ops and condos. In a co-op, the obligation runs through the shareholder relationship and the proprietary lease. In a condo, it runs through real-property ownership, the condominium documents, and the signed alteration agreement. That is one reason the 2026 condo form was written separately rather than simply reusing the co-op form.

Financial obligations

The costs tied to the alteration agreement sit outside the construction contract.

The building usually holds a security deposit during the renovation. The deposit is a reserve against damage to common areas, extra supervision costs, unpaid fees, or other obligations under the agreement. It is returned after the work is complete, the building's representative confirms that common areas were left intact, and the required closeout documents have been submitted.

In practice, many buildings ask for a security deposit in the $1,000 to $5,000 range for standard projects. Larger renovations may require higher deposits, deposits based on a percentage of project cost, or a performance bond. The alteration agreement controls the actual amount.

Managing agents also often charge a non-refundable administrative fee for processing the application. That fee is commonly a few hundred dollars, though it varies by building. The building's reviewing architect or engineer charges a separate fee for plan review. That review fee is usually non-refundable and is owed whether or not the project ultimately moves forward.

Including these costs in the overall project budget alongside design and construction gives a more accurate picture from the start.

Completion requirements

Most alteration agreements set a deadline for finishing the work. The NYC Bar condo model states explicitly that the required completion date is "time being of the essence." Missing the deadline can lead to board action, fines, extension fees, loss of construction access, or other remedies stated in the agreement.

Completion windows commonly run around 90 to 120 days for standard-scope work, though the number varies by building, project type, and what the board approved. More complicated projects may receive longer windows. Buildings may also restrict work during holidays, summer months, major building projects, or other blackout periods.

At completion, the agreement usually requires documentation in addition to confirming that common areas were left intact.

The first common item is as-built drawings. As-built drawings show what was actually constructed. They may differ from the originally approved plans if your architect, engineer, or contractor made approved adjustments during the work. The NYC Bar model co-op agreement added an as-built requirement in its 2010 revision. As-builts become the building's record of what is behind your walls and can matter for future work, repairs, leaks, sales, and building-system access.

The second common item is permit closeout documentation, for work that required permits. For a standard Alteration filing, that usually means a Letter of Completion. For work that changed the building's legal occupancy record, that usually means a new or amended Certificate of Occupancy. Other sign-offs may be required depending on the work, such as plumbing, electrical, fire alarm, sprinkler, Landmark approval, or other agency closeout.

The security deposit is usually not released until the managing agent has the required completion materials in hand and the building confirms that no common-area damage or unresolved obligation remains.

When you sell the apartment, the alteration agreement obligations can follow the work. An assumption agreement signed at closing may transfer ongoing maintenance, repair, and restoration responsibilities to the new owner. In a co-op, the managing agent often coordinates this through the share transfer process. In a condo, the transfer process works differently, but buyers and their attorneys still review alteration agreements during due diligence. Addressing the assumption agreement in the closing checklist avoids a last-minute discovery.

When the alteration agreement process is incomplete

The process can be incomplete in several ways. A prior owner may have done work without board approval. A renovation scope may have expanded beyond what the agreement covered. A contractor may have started before the agreement was fully executed. An owner may not have known the requirement existed at all. The consequences generally follow a similar pattern regardless of how the gap occurred.

Co-op boards have broad authority under the proprietary lease. When work was done outside the approved scope or without an executed agreement, the board can require access for inspection, demand corrective work, assess fees where the governing documents allow, or take other action provided by the proprietary lease and house rules.

Condo boards generally operate under more constrained authority, but the declaration, bylaws, and signed agreements still give them tools to address the same situations, including requiring compliance, demanding insurance documentation, imposing charges where authorized, or pursuing remedies provided by the condominium documents.

The consequences can also carry into a future sale. Buyers' attorneys commonly ask whether board approval was in place for renovation work in the unit and whether permits were issued and properly closed. If those questions reveal gaps, the transaction may need to pause while the issue is resolved, whether through retroactive approval, corrective work, or other means negotiated between buyer and seller.

Working through the agreement

The most useful time to work through the alteration agreement is before the design is far along. Many owners encounter it after design has already started, which is workable but not the easiest sequence.

Whoever is coordinating the project, whether that is the owner managing the process directly, a contractor handling the application, or a licensed architect, the starting point is the same. Request the building's alteration package before the design is underway. The package tells you what drawings are required, what restrictions apply, how the building handles scheduling, what insurance is needed, and what the review timeline looks like. Those answers shape the design, the schedule, and the contractor selection.

When a licensed architect is involved, they can prepare the drawings required for submission, respond directly to the building's reviewing professional on technical questions, and coordinate the building approval with any city permits the work requires. Direct communication between the architect and the building's reviewer tends to move faster than routing questions through other channels, because both parties share technical language and each understands what a complete response requires.

The closeout requirements in the agreement apply at the end of every project, regardless of who managed the approval process. As-built drawings, permit closeout documentation where permits were required, and confirmation that common areas were left intact all need to be in order before the security deposit is released. Tracking those items as the project approaches completion, rather than assembling them after the fact, keeps the closeout on schedule.

The alteration agreement has its own timeline, requirements, and review process. Accounting for them early in the project schedule, before contractor start dates are set and before the design is complete, keeps the renovation coordinated from the start.