NYC Condo Alteration Agreement Guide — Not the Same as a Co-op, Here's Why

Most New Yorkers use "condo" and "co-op" as if they were two flavors of the same thing. They are not. A condominium is real property that you own in fee simple, held under New York's Condominium Act (Real Property Law Article 9-B¹). A co-op is shares in a corporation plus a proprietary lease — you are a tenant of a building you partly own on paper. That legal distinction changes what your board can demand when you want to renovate, how much discretion they have to say no, and which clauses survive when your alteration agreement goes sideways.

If you're reading this, you probably already have companion pillars bookmarked — the NYC co-op alteration agreement guide and the NYC brownstone whole-home renovation guide. Keep them. Condo rules cross-reference both. But do not assume they substitute. The rules below are condo-specific, and they are the ones your building manager will actually hand you.

Condo vs co-op — the legal distinction that changes everything

The foundation matters before the paperwork does.

A New York condominium unit is real property. You hold fee simple title to the airspace defined in the declaration, you hold a percentage interest (the "common interest," typically expressed as a fraction — "23/10,000ths of the common elements") in the building's shared structures, and you pay common charges instead of maintenance. Title is recorded with the City Register. You can mortgage, sell, lease, or bequeath your unit without shareholder approval in most declarations. Your rights derive from the offering plan, the declaration, the bylaws, and Real Property Law Article 9-B¹.

A co-op is a different animal. The building is owned by a corporation. You buy shares in that corporation proportionate to your apartment, and the corporation grants you a proprietary lease. Legally, you are a lessee. The board's power to approve alterations, sublets, refinancing, and sales flows from the lease and Business Corporation Law. That is why co-op boards can reject buyers without stated reason and why co-op alteration agreements run 40 to 80 pages.

Practically, the implication for renovations is this: condo boards have narrower authority. They can regulate anything touching common elements — the façade, the roof, structural slabs, plumbing risers, gas lines, shared HVAC, exterior windows — because those elements belong to the condominium, not to you. They cannot regulate the inside of your unit nearly as tightly as a co-op board can regulate the inside of a shareholder's apartment. A condo board cannot reject your paint color. A co-op board, under the right proprietary lease, often can.

This does not mean condo renovations are unregulated. It means the leverage is different. Your condo board's power runs through three instruments: (1) the alteration agreement you will be asked to sign, (2) the bylaws and house rules already binding on you, and (3) the NYC Department of Buildings, which the board will require you to satisfy before it releases your permits.

What the condo board alteration agreement actually contains

A typical NYC condo alteration agreement runs 10 to 25 pages. Shorter than a co-op's, longer than a homeowner would expect. It is a binding contract layered on top of the bylaws, and you sign it before any work starts. Every condo board has its own template, but the clauses cluster predictably.

Scope of work. A narrative description of what you're building plus a set of drawings — architectural, structural if applicable, mechanical — attached as an exhibit. The scope you sign is the scope you're bound to. Expanding mid-project means an amendment, which means more fees and usually more time.

Working hours. Almost every Manhattan condo restricts construction to 9 a.m. through 5 p.m. Monday through Friday. No weekends, no federal holidays, no Jewish holidays in buildings with large observant populations. Some condos allow Saturday work with prior notice and a surcharge; most don't. Your schedule is built around this constraint, not around your contractor's preference.

Tenant-protection deposit. A refundable deposit held by the board against damage to common elements — elevators dinged during deliveries, hallway carpet stained by dropped mortar, lobby tile cracked by a dolly. Typical range is $2,000 to $25,000 depending on building class and scope. Returned after final inspection minus documented damage.

Insurance. Your contractor, and often your design team, must carry Commercial General Liability naming the condominium association and the managing agent as additional insureds. Limits typically $1M per occurrence and $2M aggregate for smaller work, $5M aggregate for gut renovations in high-end buildings. Workers' compensation and disability coverage are non-negotiable under New York law. The Certificate of Insurance goes to the board before work begins, and most boards verify the certificate directly with the carrier.

Permit requirement. You must provide the board a copy of every NYC DOB filing and every approved permit before work begins. Boards will often hold your alteration agreement hostage pending DOB approval, which matters because DOB turnarounds are slower than board turnarounds.

Contractor licensing. Your general contractor must be registered with the NYC Department of Buildings (Home Improvement Contractor license issued by the NYC Department of Consumer and Worker Protection, and for residential work above certain thresholds, a DOB registration). Boards commonly require an additional filter: prior condo experience in the specific building or in a comparable Class A elevator building.

Professional licenses. Structural work requires a New York State licensed professional engineer. Anything involving life-safety, egress, or change of use requires a registered architect (RA). These licenses are verifiable through the New York State Office of the Professions². Plumbing work requires a Licensed Master Plumber. Electrical work requires a Licensed Master Electrician. Those last two are separately licensed by the NYC Department of Buildings³.

Delay penalties. Most agreements include liquidated damages for overrunning the stated completion date — $250 to $1,000 per day is typical, with some luxury buildings (15 CPW, 432 Park, 220 CPS) running higher. The board will not waive these without cause.

Service shutoffs. Water, gas, and electrical service to the building riser cannot be shut down without 72-hour written notice to the managing agent and to every affected unit. Violations trigger immediate work-stop orders and forfeiture of deposit.

Read every clause twice. In most disputes the clause you skimmed is the one the board will invoke.

NYC DOB — ALT-1 vs ALT-2 vs ALT-3 filings

The NYC Department of Buildings classifies alterations in three tiers⁴. Your contractor will tell you which tier applies, but you should understand the difference because it drives your timeline more than anything else.

ALT-1. Major alteration. Required when the work changes use, occupancy, or egress, or involves significant structural modification. Converting a commercial unit to residential, adding a floor, combining two units into one, changing the Certificate of Occupancy — all ALT-1. Filed by a registered architect or professional engineer. Review and approval typically 4 to 6 months, longer if the project triggers Board of Standards and Appeals variances or zoning overlays.

ALT-2. Interior alteration with multiple trades but no change in use, occupancy, or egress. The typical condo kitchen-and-bath gut renovation falls here. Plumbing, electrical, and minor structural modifications like removing a non-bearing wall are covered. Filed by an architect or engineer. Review and approval 4 to 10 weeks.

ALT-3. Minor alteration. Cosmetic only — no structural, no plumbing relocation, no electrical additions beyond like-for-like replacement. Repainting, refinishing floors, replacing a toilet in the same footprint, swapping a cooktop. Many condo boards still require you to sign an alteration agreement even for ALT-3 scope, because the delivery and debris rules still apply.

The filing tier is not negotiable. Your architect will make the determination based on what's drawn. If you push for ALT-2 to avoid ALT-1 timelines when the work actually warrants ALT-1, you will hit a DOB audit on inspection and stop work for weeks while you refile. That is not a theoretical risk — it is a common error in Manhattan condo work and it costs three to five times what proper classification would have.

Plumbing, electrical, and gas permits (DEP + DOB + Master licenses)

The permits on top of the permit.

Plumbing work in NYC requires a NYC Department of Environmental Protection plumbing permit in addition to the DOB filing⁵. Any change that affects the water supply riser, the waste line, or the venting through the roof is regulated. The Licensed Master Plumber pulls the DEP permit in their name — they are on the hook if work is non-compliant, which is why Master Plumbers vet jobs carefully before signing on. Kitchen relocations and bathroom additions are the most common triggers. A like-for-like fixture swap in the same footprint usually is not.

Electrical work requires a NYC DOB electrical permit and a Licensed Master Electrician of record³. Any new circuit, any panel upgrade, any 240V appliance installation, and any low-voltage whole-home wiring requires the permit and the inspection. Master Electricians in New York are licensed and renewed by the DOB. Verify before signing a contract.

Gas work is the tightest of the three. Since Local Law 152 of 2016, gas piping systems in buildings of certain ages and sizes must be inspected by a Licensed Master Plumber on a four-year cycle, with inspection certificates filed with DOB⁶. Any alteration to a gas line triggers a permit, an inspection, and a pressure test before reconnection. Gas reconnection after a renovation can take weeks because Con Edison and the DOB each have sign-off points. Plan for this gap — you will be on electric cooking for the duration if you touch gas lines.

Local Law 97 — why your board may block gas appliances

This is the trap most condo buyers do not see coming.

New York City's Local Law 97⁷ caps greenhouse-gas emissions from buildings over 25,000 square feet. Phase 1 limits went into effect in 2024. Phase 2 limits, effective 2030, are roughly 40 percent stricter. Buildings that exceed their cap pay $268 per metric ton of CO2-equivalent over limit, per year. For a typical Class A Manhattan condo tower over 300,000 square feet, a single bad year can mean six-figure penalties allocated across unit owners through common charges.

Boards have responded predictably. Many are now rejecting alteration proposals that add gas appliances — new gas ranges, gas dryers, gas fireplaces — because adding combustion load at the unit level increases the building's aggregate emissions. Boards are also rejecting gas-fired boiler replacements during ALT work, steering owners toward heat pumps and electric equipment.

If your renovation proposes a gas appliance, expect scrutiny. Expect a request for a whole-building emissions impact analysis. Expect some boards to flat-out deny. The answer, in most 2026 Manhattan condo renovations, is to design all-electric from the start. Induction ranges are now faster than gas. Heat-pump dryers are standard in Europe. The one remaining holdout — professional-grade gas ranges — is increasingly served by high-powered induction plus a dedicated 240V circuit. Plan accordingly.

Smaller buildings — under 25,000 square feet — are largely exempt from LL97, so boards there are less restrictive. Check your building's square footage in the offering plan or on the DOB property profile before you assume.

LPC Certificate of Appropriateness if building is landmarked

If your condo building is a designated New York City landmark or sits within one of the 150+ NYC Historic Districts (covering 38,000+ buildings)⁸, any work visible from a public right of way requires approval from the Landmarks Preservation Commission before DOB will issue permits.

LPC has three approval tiers. A Permit for Minor Work covers in-kind repair and non-visible interior work that affects protected features. A Certificate of No Effect covers work that does not affect protected architectural features. A Certificate of Appropriateness is the full public hearing — required for anything altering the external appearance. Window replacements, façade repairs, visible rooftop additions, sidewalk work, and ADA-required modifications on historic façades all go to LPC.

Interior work in a landmarked condo building typically does not need LPC approval, with one exception: designated interior landmarks. These are rare in residential buildings but exist — some pre-war lobby spaces and certain hallway treatments at buildings like the Dakota (though that is a co-op) and the Ansonia carry interior protection. Check the LPC designation report for your building before assuming interior scope is LPC-free.

Your architect files with LPC. Expect 4 to 8 weeks for a Certificate of No Effect, 3 to 6 months for a Certificate of Appropriateness that requires a hearing. LPC approval must precede DOB approval — the DOB filing will stall without the LPC stamp.

Structural work in a high-rise condo — shear walls and load path

The phrase "gut renovation" gets used loosely in condo marketing. In a high-rise the reality is more constrained.

Post-war and modern high-rise condos in Manhattan are almost universally built with reinforced concrete or steel moment-frame structures. Many of the walls inside your unit are not partition walls — they are shear walls, doing work against lateral wind and seismic loads. Removing one is not a matter of carrying load on a header beam; it changes the building's lateral force resistance. Engineering analysis is required. In some buildings, the answer is no.

Pre-war high-rises (pre-1940) have load-bearing masonry and column grids that sometimes allow more interior flexibility but impose different constraints — the columns are where they are, and they are not moving. Slab penetrations for plumbing relocations require engineering review because the slab is structural and post-tensioned in many later buildings (cutting a post-tensioned slab without analysis can cause a catastrophic failure).

The workflow is: your architect flags structural scope, a licensed professional engineer files with DOB, the condo board receives the engineer's report, and in most buildings a party-wall notice is served on every unit sharing a wall with the work. Adjacent owners have a right to review. They rarely block, but they do occasionally escalate. Budget for this process — 4 to 8 extra weeks on top of ordinary DOB timelines.

The practical implication: "open concept" is easy in a 1920s brownstone and hard in a 1985 Midtown tower. Before you commit to a layout, have a structural engineer walk the unit. Do not rely on your contractor's judgment alone. Contractors do not carry professional liability; engineers do.

Sponsor-unit rules in newer condos

Condos built or converted after 2010 often carry Sponsor Unit provisions in the offering plan. These typically run for 5 to 10 years after the initial closing. During the sponsor-retention period, the sponsor — the original developer — retains rights that the condo board does not have: unrestricted sublet, veto over significant building-wide decisions, and in some offerings, approval rights over alterations to sponsor units that are still held unsold.

If you bought from the sponsor after conversion, your unit may still be in the sponsor window. Check your closing documents. If the sponsor has a right of approval over your alteration scope, it is additive to board approval, not a substitute. Sponsors are harder to reach than boards and slower to respond. Build 2 to 4 extra weeks into your approval timeline if sponsor rights are in play.

Newer condo declarations also often carry "first alteration" riders that impose additional conditions on the first post-closing renovation of a unit — heavier tenant-protection deposits, stricter working-hours windows during building punch-list phase, required attendance at a pre-construction meeting with the sponsor's architect. Read the rider. It is separate from the alteration agreement.

Cost bands: $85K to $800K+ by scope

The 2026 Manhattan condo numbers, grounded in actual recent project quotes.

Kitchen renovation. Mid-range condo (Upper East Side, Upper West Side, Midtown South), 100 to 150 square foot kitchen, mid-grade cabinetry, stone counter, Bosch-tier appliances: $85,000 to $180,000. High-end (Tribeca, 15 CPW, 432 Park, 220 CPS), custom cabinetry, imported stone, Gaggenau or Sub-Zero/Wolf, integrated appliances, full electrical upgrade: $180,000 to $450,000.

Bathroom. Primary bath, 60 to 90 square feet, mid-grade stone, Kohler-tier fixtures, walk-in shower: $40,000 to $80,000. High-end primary with wet-room, steam, heated floors, imported stone, Waterworks fixtures: $80,000 to $120,000. Powder room $20,000 to $45,000.

Full gut renovation. 2-bedroom, approximately 1,200 square feet, mid-range finishes, no structural changes: $150,000 to $350,000. Same footprint, high-end finishes, interior layout changes, full MEP replacement: $350,000 to $800,000+. Large combinations (2-unit combination into 1, 3,000+ square feet) run $800,000 to $2M+.

Service elevator booking. Separate cost from construction but essential to plan. Most Manhattan condos require service elevator reservation 2 to 6 weeks ahead for major deliveries — millwork, stone slabs, appliances. Some buildings charge $500 to $2,000 per service-elevator day; others include it in common charges. Failing to book means trucks sitting on 57th Street while your installer racks the meter.

These are working ranges from actual 2026 project files. They are not floors or ceilings. They do move with finish selection, scope creep, and the specific board's fee schedule.

Timeline: board 2-8 weeks + DOB 4-24 weeks + build 3-14 months

Sequence matters. Parallelism helps where it can, but board and DOB approvals must come before trade work.

Pre-design: 2 to 4 weeks. Contractor walk-through, measurements, preliminary engineering if structural scope is suspected.

Design development: 6 to 14 weeks. Architect drawings, interior design selections, mechanical coordination. Do not skip this phase. Most overruns are caused by under-developed drawings, not by contractor error.

Board alteration agreement: 2 to 8 weeks. Package submission to managing agent, board review, comments returned, resubmission, signing, deposit paid. Busy buildings with active boards can turn this in 2 to 3 weeks. Quiet boards that meet monthly can take 8.

DOB filing and approval. ALT-3: 2 to 4 weeks. ALT-2: 4 to 10 weeks. ALT-1: 4 to 6 months. LPC approval, if required, adds 4 weeks to 6 months in parallel with DOB.

Permit pull. 1 to 2 weeks after DOB approval.

Construction. Kitchen-and-bath only: 3 to 6 months. Kitchen, bath, and some interior reconfiguration: 4 to 9 months. Full gut, 2-bedroom: 6 to 12 months. Large combinations or significant structural work: 10 to 14 months, occasionally longer.

Close-out. Final DOB inspection, Certificate of Occupancy or Letter of Completion if required, board final walkthrough, deposit return. 2 to 6 weeks.

Total realistic window from first contractor call to key-in-door on a mid-range 2-bedroom gut renovation in a Manhattan condo: 10 to 16 months. Anyone promising faster is either cutting a corner you'll pay for later or ignoring your board's timeline.

What Baily verifies before any NYC condo match

Angi sends your information to 12 contractors. Baily sends it to one — the right one — after verifying the following for every NYC condo job.

NYC DOB contractor registration. Active and in good standing, with the correct license class for the scope of your project. We pull the registration directly from DOB before the match, not from a contractor's profile page.

Prior NYC condo experience. Not suburban townhouses, not Brooklyn brownstones — NYC Class A condo work in buildings of similar age and structural type to yours. A contractor who has done 40 Williamsburg loft conversions is not automatically the right fit for a pre-war UES condo with a strict board.

Specific condo-board experience. Every NYC condo board has institutional memory. Boards remember contractors who ran overnight, who tracked debris through the lobby, who ignored service-elevator rules. Our match considers not just building class but, where possible, prior work in your specific building.

Master Plumber and Master Electrician subcontractor network. Verified active NYC licenses for the trades that will pull permits in their names. Gas work specifically requires an LL152-compliant plumber of record.

Architect and engineer bench. For ALT-1 and ALT-2 scope, we verify the design team's New York State registrations² and their history of DOB filings in the last 24 months. Active practice matters — an architect who has not filed in NYC in three years will struggle to move your project.

Insurance. COI on file with correct coverage limits and additional-insured language consistent with what your board will require.

Financial stability. Contractors who go under mid-project are a real risk in NYC given the front-loaded deposit structure. We look at Better Business Bureau records, lien history in the NYC County Clerk and Supreme Court indices, and active lawsuit activity.

One match. One introduction. No bidding war, no 12 phone calls, no sales pitch. If the match is wrong, we re-match without charge and without your information being re-sold.

That is the contract. Start by telling Baily about your project.

---

FAQ

What's the legal difference between a condo alteration and a co-op alteration in NYC?

A condo alteration happens in real property you own fee simple — you hold title to the unit itself, plus a percentage interest in common elements like the lobby, roof, and facade. A co-op alteration happens in shares of a corporation under a proprietary lease — you own stock, not the apartment. Practically, this means condo owners have more latitude to alter the interior of their unit, but anything touching common elements (ductwork, plumbing risers, structural walls, exterior windows) still needs condo board consent and NYC DOB permits. Co-op boards typically have broader veto rights under the proprietary lease than condo boards have under the condo declaration and bylaws. Both require board consent for most structural work, but the scope of board discretion is different.

Do I need board approval for a simple cosmetic renovation in my condo?

Usually yes, even for ALT-3 scope. Most NYC condo bylaws require a signed alteration agreement for any work involving contractors in the building, regardless of whether the work itself needs a DOB permit. The reason is not the work — it is the logistics. Deliveries, debris removal, noise, service-elevator bookings, and contractor access to the building all need to be regulated whether you're repainting or gutting. A truly minor task (hanging curtains, assembling furniture) typically does not. A painter spending two weeks in your unit does. When in doubt, ask your managing agent before work begins. Unauthorized work is the fastest way to trigger a board dispute and a stop-work notice.

What triggers Local Law 97 exposure in my condo renovation?

Local Law 97 applies to the building, not to your individual unit, so your renovation does not typically put you personally on the hook for emissions penalties. But your renovation can add to the building's aggregate emissions, which the board then allocates to all unit owners through common charges. The specific triggers boards watch for are adding gas appliances (gas range, gas dryer, gas fireplace) that did not previously exist, replacing an efficient electric system with a gas system, and increasing HVAC load through additional cooling capacity. If your building is over 25,000 square feet (most NYC condo towers are), expect the board to scrutinize any combustion load added. Designing all-electric from the start avoids this fight.

How much does a typical 2-bedroom condo gut renovation cost in Manhattan in 2026?

Working ranges, with no structural changes and mid-range finishes, $150,000 to $350,000 for a roughly 1,200 square foot 2-bedroom. With interior layout changes, full MEP replacement, and high-end finishes (custom cabinetry, imported stone, Gaggenau or Sub-Zero/Wolf appliances, Waterworks fixtures), $350,000 to $800,000+. Two-unit combinations into a single 3,000+ square foot home run $800,000 to $2M+. These are real project numbers from 2026 Manhattan condo jobs, not sales estimates. Your actual number depends on finish selection, scope creep during drawings, and your specific board's fee schedule — some buildings charge $5,000 to $15,000 in review fees on top of your tenant-protection deposit.

Can my condo board actually force me to use their preferred contractor?

No — not legally. A condo board cannot dictate that you hire a specific contractor. What they can do is set requirements that any contractor must meet: NYC DOB registration, minimum insurance limits, prior experience in Class A buildings, compliance with the alteration agreement, attendance at pre-construction meetings. Those requirements are enforceable and are often specific enough to narrow the candidate pool. Some boards maintain a "suggested contractor" list of firms that have worked in the building and have a track record the board trusts — you are not required to pick from that list, but choosing from it typically speeds board approval by 2 to 4 weeks. If your board is trying to compel a specific contractor outside of stated requirements, that is a legal overreach and grounds for pushback with your real estate attorney.

---

Footnotes

1. Real Property Law Article 9-B (Condominium Act), New York State Senate. https://www.nysenate.gov/legislation/laws/RPP/A9-B ↩ ↩²

2. New York State Office of the Professions — license verification for architects, professional engineers, and design professionals. https://www.op.nysed.gov/verification-search ↩ ↩²

3. NYC Department of Buildings — Licensed Master Plumber and Licensed Master Electrician registration and lookup. https://www.nyc.gov/site/buildings/industry/licensed-master-plumbers-and-fire-suppression-piping-contractors.page ↩ ↩²

4. NYC Department of Buildings — Alteration filings (ALT-1, ALT-2, ALT-3) and Job Filing overview. https://www.nyc.gov/site/buildings/industry/alteration.page ↩

5. NYC Department of Environmental Protection — plumbing permits and water/sewer connection requirements. https://www.nyc.gov/site/dep/business/plumbing-inspections-permits.page ↩

6. NYC Local Law 152 of 2016 — gas piping system inspections. https://www.nyc.gov/site/buildings/codes/local-law-152.page ↩

7. NYC Local Law 97 of 2019 — Greenhouse Gas Emissions Limits for Buildings, NYC Mayor's Office of Climate & Environmental Justice. https://www.nyc.gov/site/sustainability/codes/local-law-97.page ↩

8. NYC Landmarks Preservation Commission — Certificate of Appropriateness, Certificate of No Effect, and Permit for Minor Work. https://www.nyc.gov/site/lpc/applications/permit-application.page ↩