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Armorie at 114 East 25th Street, the Flatiron Building, and a listing at The Aman New York are among NYC's most recent office-to-condo developments Armorie at 114 East 25th Street, the Flatiron Building, and a listing at The Aman New York are among NYC's most recent office-to-condo developments

While New York City’s office market remains in flux, new reports indicate that office demand has finally stabilized. However, a "flight to quality" is reshaping the landscape, with business leaders prioritizing premium office spaces to attract and retain talent in the era of hybrid work. As a result, landlords of aging Class B and C buildings are exploring ways to revitalize their properties. Converting outdated offices into residential homes has long been seen as a promising solution—but the challenges of such transformations are daunting, both financially and logistically.

 

We sat down with Matthew Adell, CEO and founder of Adellco, to discuss what makes a successful office-to-residential conversion, the challenges developers face, and how these transformations will shape the future of the city.


In this article:

One Hundred Barclay Tribeca, 100 Barclay Street
One Hundred Barclay Tribeca, 100 Barclay Street Tribeca
Liberty Tower, 55 Liberty Street
Liberty Tower, 55 Liberty Street Financial District
49 Chambers Street
49 Chambers Street Tribeca
45 West 81st Street
45 West 81st Street Central Park West
The Clocktower Building, 1 Main Street
The Clocktower Building, 1 Main Street DUMBO
Flatiron Building conversion The Flatiron Building, which is undergoing an office-to-condo conversion by The Brodsky Organization. Taken from the Sohmer Piano Building, a completed office-to-residential conversion (Douglas Elliman)
Ondel: Many recently announced office-to-residential projects have been rentals. What makes a condo conversion viable?
Matthew Adell: It all comes down to economics, specifically acquisition costs and market demand. There is clearly a shortage of housing in New York, and rental housing is needed everywhere. The key questions are: What is the supply in the submarket? What are the fundamental costs of conversion? If the numbers work, condos can absolutely make sense. 

 

 As a developer and investor, we [Adellco] are always looking to find the highest and best use for a property. Taking older office stock that is stressed or distressed and finding a higher and better use is what we do all the time. While converting to other commercial uses is an option, residential conversion is often the best path to rescuing a distressed office building.


Ondel: Are certain New York City commercial districts better suited for conversions?
Matthew Adell: It’s less about the neighborhood and more about the specifics of each project. One major hurdle is lease commitments—some tenants don’t want to relocate, which can limit what an owner can do. A landlord must determine if they have the legal right to vacate tenants or if they can phase the project while some tenants remain. 

 

 For us, we focus on what’s legally possible rather than negotiating with tenants. Some buildings generate enough net operating income to remain viable until leases expire. Buying an occupied building with the intent of converting sometime in the future can be a less risky move

The Financial District is already home to many office-to-residential transformations

Ondel: For small- to mid-sized office buildings, does it make more sense to demolish and rebuild rather than convert?

Matthew Adell: It depends. Residential floor plates are very different from office floor plates. Large, deep layouts that worked for office tenants may not be easily adapted for livable apartments. 

Every building is unique, and marketability is a big factor. Sometimes reconfiguring the building envelope is feasible, where you can reduce the square footage of certain floors and then hopefully putting the square footage on top or somewhere else. Understanding what the final square footage will be and if you will recover any loss of floor space with sales income is crucial.

 

The feasibility of converting offices to any other use is very building specific. One must weigh the cost of reconfiguring the exterior, the elevator, stair, and mechanical core, while providing the units with enough light. Sometimes it's best to demolish. There’s just no way to generalize.


Woolworth building The Woolworth Tower Residences, where in 2018, the slender upper portion of the Woolworth Building was converted into 32 condos starting on the 29th floor by developer Alchemy Properties and architect Thierry W. Despont
Ondel: What factors would make a condo conversion more viable than a rental one?

Matthew Adell: Whether a condo project pencils out is determined by the cost of the market tier the developer is venturing in.

In rental conversions, longer hallways and efficient spaces may be feasible. However, to create more generously sized residences, developers must carefully project how much revenue each unit can generate per square foot. Creating a unit that is too large may result in an apartment that exceeds market demand.

Condominium buyers consider both price per square foot and the overall cost of a unit. Oversized residences are neither inherently good nor bad, but the market must support them.

Sometimes, you have a beautiful old building that cannot be replicated. If there is value in preserving it and the market is likely to respond positively, then a condo conversion may very well be viable.

 


Emmet Building The ornate Emmet Building at 95 Madison Avenue is currently undergoing a condo conversion
Ondel: Last year, the state and the city announced the launch of the Affordable Housing from Commercial Conversion Tax Incentive Benefit (467-m) program, a tax incentive to encourage residential conversions. SL Green’s CEO estimates that 20 to 40 million square feet of office space could potentially be converted with the help of such incentives.
Matthew Adell: It’s a valuable incentive program, but I don’t think developers will take on projects they wouldn’t have otherwise pursued. The program may help offset interest rates or affordable housing requirements, but I don’t foresee a flood of projects as a direct result. We’ll have to see how many conversions actually move forward.

A section of a newly redesigned plaza block on Broadway, from East 17th Street to East 18th Street. (Credit: NYC DOT)
Ondel: How do you see these conversions impacting the city?
Matthew Adell: I think it’s healthy, I see it as a positive shift. Conversions are an attractive proposition for the city. What drives any urban or suburban market is a balanced combination of job opportunities and living space. 

 

 

There’s no risk of oversupply — New York has a persistent housing shortage, unlike some other markets. I really can’t think offhand of anything negative about introducing more homes. It creates a more 24-hour environment, and I also don’t think business districts will fundamentally change because of residential conversions.

 

 

I also appreciate how the city has been making some streets more pedestrian-friendly with plazas and landscaping. That, combined with more residential conversions, makes for a more vibrant urban environment.

 


114-east-25th-street Adellco is converting 114 East 25th Street from a co-working office space, which opened just before the pandemic, into condominium residences. (Credit: Mancini Duffy Architects)
Ondel: You just completed The Wales, a hotel-to-condo conversion. What’s next?
Matthew Adell: Yes, we were ahead of the curve on converting obsolete commercial buildings. Our next project at 114 East 25th Street, off Park Avenue South, is an office-to-residential conversion launching early this year. The building was a great candidate — minimal interior modifications were needed, and we didn’t have to alter the perimeter.

Recently announced office-to-condo conversions


Armorie

114 East 25th Street, Flatiron District

Anticipated Sales Launch: Q1 2025

114-east-25th-street Armorie, Adellco's new office-to-condo conversion in the Flatiron District
Developer Adellco is converting a former co-working office building at 114 East 25th Street in the Flatiron District, into 20 loft condo residences, newly named Armorie. Originally constructed in 1921, this 14-story former publishing house between Park Avenue South and Lexington features a brick facade with keystone accents that honor the rich Beaux-Arts style. The project is being reimagined by Andre Kikoski Architecture (AKA), the firm behind the fast-selling 75 Kenmare in NoHo, and Adellco. The 20 homes will include one- to four-bedroom homes with a penthouse and an enviable private rooftop terrace. Occupancy is slated for early Q1 2026.
114-East-25th-street-amorie Ongoing work in Dec. 2024 for the conversion of 114 East 25th Street into the Armorie condo residences (CityRealty)

Flatiron Building

185 Fifth Avenue, Flatiron/Union Square

Anticipated Sales Launch: Late 2025/2026

Perhaps the most anticipated and drama-filled conversion is the iconic Flatiron building. Designed by Daniel Burnham and Frederick P. Dinkelberg in 1901, the Beaux Arts Flatiron condo conversion is expected to be completed in 2026. Originally dubbed “Burnham’s Folly”, the Flatiron has always presented a challenge for space making, due to its triangular, flatiron-like shape.

According to filings, the conversion will not involve any demolition, addition, or expansion, just “minor exterior work” and interior renovations to convert the expansive office floors to smaller, more insular layouts. Additionally, the building only has one stairwell so another needs to be installed for safety code. Currently, the interior spaces are floor-through cavernous, tapered triangles. The ground floor will remain commercial, the upper 21 floors will be residential. 

The developers, the Brodsky Organization, GFP Real Estate and the Sorgente Group, aim for residents moving in by the end of 2026, according to the New York Observer.

 


Emmet Building

95 Madison Avenue, Gramercy Park

Anticipated Sales Launch: TBD

Located at 95 Madison Avenue in NoMad, the 1912 Emmet Building was home to the pre-eminent American gynecological surgeon of the last quarter of the 19th century, Thomas Addis Emmet. Last week, The Real Deal reported the 16-story limestone was designated as a landmark in 2018 and will be converted into 65 condos. Sizes and prices have yet to be announced.
Emmet Building Construction prep work underway as of December 2024

The Elad Group plans to convert this 200,000-square-foot former WeWork office building into around 100 condo units. The previous WeWork space spanned seven light-flooded floors with art-filled lounges, conference rooms, private offices and soundproof phone booths (wonder if they’ll keep any of that?).

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While not an office conversion, Emmut Properties is undertaking the conversion of 45 West 81st Street, the former Hotel Standish Hall on the Upper West Side. The 1922-built mid-block tower will house 143 condos. The 15-story building overlooks the American Museum of Natural History and is a half a block of Central Park has been described as both Spanish Renaissance and neo-Moorish and was named after Myles Standish, the captain of the Mayflower.

An offering plan has been approved, and sales are anticipated to launch early 2025. Prices will range from about $650K for an efficient studio to over $13.5 million for a palatial four-bedroom penthouse.
45 West 81st Street

Built in 1990, 623 Fifth Avenue—also known as the Swiss Bank Tower (after the bank that occupied the building until 2006)—is a 36-story limestone tower that will be converted into 172 condominium units on the top 26 stories. The bottom 10 floors will remain Saks retail. In their most recent filing, the Cohen Brothers noted that the building’s small and narrow floor plates make it a prime candidate for residential conversion. There is currently an application with the NYC Department of City Planning seeking zoning changes to facilitate the conversion.

RJ Capital Holdings and Top Rock Holdings have filed plans to convert a 14-story office building at 609 Fifth Avenue into a 29-story mixed-use tower comprising 76 ultra-luxury residential units. The development is located across the street from two iconic properties, Saks Fifth Avenue and Rockefeller Center. 

The project will add approximately 93,000 square feet to the former SL Green property, bringing its total size to about 226,000 square feet and increasing its height from 187 feet to 400 feet. Rafael Viñoly Architects, the firm behind 432 Park Avenue, is listed as the architect of record, with design featuring a series of stacked boxes and new glass facade. 

The building's new layout is slated to feature apartments on the first, third, and fifth through 28th floors, with offices on the fourth and fifth floors. The 29th floor will be used for storage. The property will include 41 parking spots for bicycles as well.


In 2016, the Chen Foundation, linked to the nonprofit T.F. Chen Cultural Center acquired a 12-story, 95,000-square-foot commercial loft building at 335 West 35th Street for $50 million. Dubbed Society House, construction begn to convert the property into a residential condominium designed by Isaac and Stern Architects. As the Garment District's first significant residential condo conversion in over a decade, the venture would offer 71 studio to two-bedroom residences with starting prices around $800,000.

Despite debuting a registration site in 2019 and garnering interest for its investment potential, central location, and proximity to various transit options as well as Hudson Yards, the project faced significant delays due to the pandemic and the developer's difficulties: The owning entity filed for bankruptcy in January 2024 but sought $15 million to $18 million to complete the development. In April 2024, they filed lawsuits against Shanghai Commercial Bank and Milestone Construction Corp. for fraud and negligence, blaming them for stalling construction on the project (h/t The Real Deal).

(Evan Joseph)

Sitting atop Grand Central Terminal, The Helmsley Building is a 35-story skyscraper built in 1929, originally known as the New York Central Building and designed by Warren & Wetmore, who also designed Grand Central in a similar Beaux-Arts style. The landmarked, 34-story debt-burdened building has a stunning marble and bronze lobby and gilded elevators. Imagine how extraordinary the penthouse will be with that copper pyramid roof capped with a cupola and wrap-around terrace. 

Its owner, RXR Realty announced plans to partially convert the building into apartments, but in December 2024, the building's mortgage lenders filed a foreclosure action in New York state Supreme Court, according to Crain's New York. A spokesman for RXR told Crain's that RXR “continues to have constructive conversations with the lenders.”

Helmsley Building The Helmsley Building which partially may go residential (Evan Joseph)


Active sale listings in recent office-to-residential conversions


Aman New York Residences, #18B (Aman Property DE)

The Sohmer Piano Building, #PH (Sothebys International Realty)

212 Fifth Avenue, #16B (Elegran LLC)

10 Madison Square West, #14F (Douglas Elliman Real Estate)

The Chelsea Mercantile, #PHD (Compass)

Mandarin Oriental Residences Fifth Avenue, #8A (Douglas Elliman Real Estate)

75 Livingston Street, #14C (Corcoran Group)

One Central Park West, #25C (Coldwell Banker Warburg)

Walker Tower, #9C (Compass)

88 & 90 Lex, #505 (Ostrov Realty Group Limited)

49 Chambers Street, #9D (Argo Residential)

Stella Tower, #15E (Douglas Elliman Real Estate)

One Wall Street, #1111 (One Wall Street Sales LLC)

One Hundred Barclay Tribeca, #11C (Compass)

The Clocktower Building, #12K (Sothebys International Realty)

Liberty Tower, #1920A (Serhant)

76 Madison Avenue, #7B (Compass)

101 Wall by the Water, #11B (Serhant)

Downtown by Starck, #2416 (Compass)

The Morse Building, #5B (Corcoran Group)

Kheel Tower, #3D (Douglas Elliman Real Estate)

Jade, #5F (Sothebys International Realty)

The Collection, #1404 (Corcoran Group)

75 Wall Street, #31P (Platinum Properties)

District, #PH103 (Compass)

South Star, #9B (Brown Harris Stevens Residential Sales LLC)

The Broad Exchange Building, #16O (Christies International Real Estate Group LLC)

Cocoa Exchange, #1309 (Douglas Elliman Real Estate)

254 Park Avenue South, #6G (Douglas Elliman Real Estate)

The Croft, #12B (Douglas Elliman Real Estate)

99 John Deco Lofts, #202 (Compass)

Greenwich Club, #920 (Compass)

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