Office-to-Apartment Conversions: A Design-Build Playground
- Gil Rosa
- Aug 29
- 4 min read
When vacant towers become housing, and builders become translators of space.
The buildings are already there.
Steel bones. Curtain walls. Deep floorplates. Empty desks.
But the tenants are gone.
Now, New York City is asking a powerful question:
What if we could turn this vacancy into vitality?
And the answer is arriving approximately 17,400 times over.
That's the number of apartment units New York City is expected to gain through office-to-residential conversions over the next several years, according to current estimates 1. This is no passing trend. It's an urban metamorphosis. And if you're in the business of building systems, teams, or cities, this is your arena.
Why This Trend Matters (and Why GRPM Is Watching Closely)
Let's discuss why this matters not just for developers and designers, but also for those who believe that building is both a craft and a calling.
1. Transformation Is the Ethos
At GRPM, we believe in transformation not just of buildings, but of teams, systems, and thinking. Converting old offices into modern housing is an act of adaptive reuse, yes, but more than that, it's an act of respect. Respect for the embodied carbon already invested. Respect for the city's evolving needs. And respect for people who deserve to live where there are jobs, transit, and a good quality of life.
2. Design-Build Is Built for This
Office conversions require nimble, cohesive teams. This is not a hand-off game. It's a relay race run together. Architects, builders, MEP consultants, energy modelers, and permit wranglers must all be in sync. Design-build excels here because it collapses silos and aligns incentives. It's not just better for the project. It's better for the outcome.
The Policy Tools Behind the Push
None of this is happening by accident. It's the result of smart, aggressive policy reform, and you need to know the tools in play:
467-m Tax Incentive: Up to 35 Years of Tax Relief
The Affordable Housing from Commercial Conversions Program offers massive tax abatements up to 90% for 35 years to developers who:
This isn't just a discount; it's a once-in-a-generation opportunity to transform old square footage into viable housing.
FAR Cap Lifted
Historically, residential development in NYC was capped at a Floor Area Ratio (FAR) of 12, which made many conversions infeasible. That cap is now lifted, unlocking sites like 5 Times Square, which is converting nearly 1 million square feet into 1,250 homes, including 313 permanently affordable units. 5.
"City of Yes" Reforms
The reforms allow conversions of buildings constructed as late as 1991, not just pre-1961 structures. This opens up huge swaths of Midtown, FiDi, and the Garment District to creative reimagination. 6.
Real Projects, Real Learnings
Let's zoom in on the practical side. This isn't theory. This is field-tested design-build with grit. They're live, messy, magnificent jobsites.
Project | Details |
25 Water Street | ~1,300 units; formerly a 1960s office tower; first to use 467-m; residents moved in February 2025 7 |
40 Exchange Place (former NYSE building) | 382 units in the Financial District; example of deep retrofitting 8 |
5 Times Square | 1,250 units including 313 affordable homes; enabled by zoning and tax incentives 5 |
Citywide Potential | Estimated 15.2 million sq ft across 44 projects, potentially creating over 17,400 homes. 1 9 |
The GRPM Take:
This Is Not a "Normal" Project Type
There are real, technical challenges to these transformations, just the kind we like to decode. Design-builders eyeing this terrain must understand the wrinkles. This isn't clean-sheet architecture, it's surgery on a living skeleton.
1. Deep Floorplates Mean Tricky Daylight
Typical office buildings are too deep for natural light to reach far into units. Solutions include carving internal courtyards, orienting units toward cores, or using innovative daylighting strategies. Your designer must think like a builder, and vice versa.
2. Plumbing, HVAC, and Egress Redesign
Office towers weren't built for stacked kitchens, baths, and bedrooms. Every system, mechanical, structural, and life safety, must be rethought. The only way to do this efficiently? Close coordination from Day One.
3. Time Is a Strategic Advantage
These conversions are finishing in 12–18 months, nearly 30% faster than ground-up construction 10. For developers, that's pure oxygen.
4. Affordability Is a Must-Have, Not a Nice-to-Have
This isn't just market-rate speculation. It's an affordable housing strategy backed by tax law. The public is watching. That means transparency, compliance, and smart, scalable systems must be baked in from the start. If you're not comfortable with compliance, public-private partnership, and affordability planning, you're not ready to lead.
Final Thought: Build More Than Units
These projects are more than math. They are modern alchemy.
Office conversions aren't just technical challenges; they're also a significant business opportunity. This is a cultural shift. A spatial rebalancing of our cities. This is the moment the role of the builder needs to expand beyond contractor, beyond cost-controller, to translator of transformation. And the Architect needs to regain the role of master builder because, we're not just swapping desks for beds. We're rewriting the story of what buildings mean. We're proving that what was built for one life can be reborn into another.
And that's a message every true builder and designer needs to understand.
Turning vacancy into vitality. Steel into sanctuary. Floorplates into futures.
The kind of work where builders must think like philosophers.
Where systems are sacred. And where transformation is not a luxury, it's the job.
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