Cost to Combine Apartments in NYC (Co-op vs Condo): Filing + Construction Explained

Thinking about knocking down walls to merge two apartments into one sprawling space? Well, there’s been a rise in popularity with apartment combinations in NYC. But the process (and price) changes wildly depending on whether you’re in a condo or a co-op. Let’s break down what you’ll face—from board battles to construction budgets—so you know exactly what’s coming.

The Co-op Conundrum: When Your Board Holds All the Cards 

Co-ops require board approval before construction begins. This process usually costs upwards of $15,000 – $35,000 in architectural and engineering costs alone and can take 3-6 months. Your architect will need to submit detailed construction plans, engineering reports, and proof that you’re not compromising the building’s integrity.

Here’s what makes co-ops particularly challenging:

• Alteration agreements that may require you to carry hefty insurance policies ($2-5 million in coverage)
• Building deposits ranging from $25,000-$100,000+ (refundable, but still a cash flow headache)
• Attorney fees for reviewing board requirements and negotiating terms ($3,000-$8,000)

Some co-op boards are notoriously difficult, requiring multiple presentations and revisions. Budget extra time and patience—you’ll need both.

Condo Combinations: Easier, But Not Exactly Simple

Condos offer more freedom since you own your unit outright, but don’t assume it’s a free-for-all. You’ll need to submit paperwork to the Department of Buildings and get some architectural approvals. Just like in co-ops, these approvals will cost between $20,000 and $40,000, but they will get approved in a shorter amount of time.

Condos typically require:

• DOB permits and filings coordinated by your architect and expeditor ($5,000-$15,000 in expediting fees)
• Engineers and architects to ensure structural soundness ($15,000-$25,000)
• Building insurance and notifications to your condo board (usually straightforward, but still mandatory)

The beauty of condos? Once your plans meet building codes, you’re generally good to go without the subjective board drama.

The Real Money: Construction Costs That Add Up Fast

Now for the big number: actual construction. Combining apartments in NYC typically costs $400–$500 per square foot, depending on finishes and complexity. For a 2,000-square-foot combination, you’re looking at $800,000–$1,000,000+ in total construction costs.

This includes:

• Demolition and structural work: removing walls, reinforcing beams, rerouting utilities ($100,000-$250,000)
• New systems: HVAC, plumbing, electrical for your expanded space ($75,000-$150,000)
• Finishes: flooring, kitchens, bathrooms, custom millwork (sky’s the limit, but budget $200,000-$500,000 minimum)

Hidden Costs Nobody Warns You About

Beyond construction, factor in moving and storage costs ($10,000-$30,000), temporary housing if needed ($5,000-$15,000/month), and the inevitable change orders that pop up mid-project (add 10-20% to your budget as a buffer).

Don’t forget closing costs if you’re purchasing the adjacent unit: $30,000-$100,000+, depending on purchase price, including mansion tax, title insurance, and attorney fees.

Making Your Dream Combination a Reality

Combining apartments transforms how you live, but it’s a marathon, not a sprint. Co-ops demand patience and political savvy, while condos offer a more streamlined path. Either way, expect to invest 6-12 months from initial plans to final walkthrough, with total costs ranging from $750,000 to $2 million+ for most projects.

The key? Work with experienced professionals who navigate NYC’s complex regulations daily. From board approvals to the final inspection, having the right team makes all the difference between a dream renovation and a nightmare.

Get your apartment combinations done right with Zicklin Contracting—NYC’s trusted experts in seamless apartment mergers. Schedule your consultation today and turn two spaces into the home you’ve always envisioned.