Adding 15 New Apartments Inside a 1920's Bronx Building

For more than a century, a 1920's Bronx building remained largely unchanged: 36 large apartments along deep corridors, with a basement used for storage and an old oil tank. The building had volume, but it wasn’t obvious.

Meltzer/Mandl Architects was hired to determine how many new, legal apartments could fit inside the existing structure. Over two and a half years, the team increased the unit count from 36 to 51, a 42 percent gain, through careful subdivision, basement conversion, and ongoing coordination with the Department of Buildings. “We looked for every opportunity the building itself would allow to add new apartments,” Meltzer says.

Understanding Where Density Could Exist

The first step was understanding which regulations applied to a building built long before modern codes. Different parts of the work triggered the 2014 Building Code, the 1968 Code, the 1955 Housing Maintenance Code, and the 1929 Multiple Dwelling Law.

Each regulated different aspects: room sizes, windows, kitchens, bathrooms, corridors, and light and air. Success depended on knowing which code applied to which condition. “It’s like reading four different rulebooks at once,” Meltzer notes. The team designed new units that met the correct criteria without triggering unnecessary upgrades.

A Constantly Moving Target

As tenants moved out, new opportunities arose. Each vacancy required fresh layout studies, DOB filings, and approvals. The project went through roughly 15 amendments, including a period when the building briefly exited TCO so another change could be filed. “Flexibility was key, every vacancy changed what was possible,” Meltzer emphasizes.

Basement Conversion

The biggest opportunity was below grade. Former storage areas and the oil-tank vault were converted into six studio apartments. To make them legal, the team decommissioned the oil tank, installed new plumbing risers, replaced gas ranges with electric, and built an ADA-compliant ramp in the public right-of-way. Natural light and ADA adaptability were added where required.

What had been a non-productive space now provides fully code-compliant housing. “We turned what was ‘invisible’ space into real homes,” Meltzer says.

Designing Micro-Units That Work

Some large apartments could be subdivided directly into two units, but others required creative solutions. In one vertical stack, physical constraints made a 1:2 split impossible. The team created duplex micro-units, turning three apartments into five.

Risers that could not be moved required layout revisions. Kitchens and bathrooms had to fit around existing piping. Each unit needed access to a corridor and egress, which in a six-story walk-up meant modifying fire escapes and, in some cases, routing them around corners.

The goal was small units that still function like full apartments, with proportioned living space, full kitchens and bathrooms, and natural light. “Even small apartments deserve to feel like homes,” Meltzer points out.

Coordinating Approvals and CO Modifications

Because the project involved reopening and modifying a century-old Certificate of Occupancy, extensive coordination with the Department of Buildings was required. Meltzer/Mandl handled approvals, inspections, plumbing permits, special inspections, and the sequence of amendments needed for a Temporary Certificate of Occupancy.

Revising an older CO is complex. Every change can trigger additional requirements. The key is understanding the code and knowing what must and must not be altered.

Outcome

This project shows how much potential exists inside older New York City buildings when code knowledge, design flexibility, and DOB strategy align. “If you understand the building and the rules, you can create far more homes than anyone expects,” Meltzer concludes. With careful analysis and adaptability, significant new housing can be created without expanding a building’s footprint.