Apartment Combination Filing NYC
How to File an Apartment Combination in NYC
Apartment combinations are one of the most common residential renovation projects in New York City — and one of the most frequently misunderstood from a DOB filing perspective. Whether you're combining two adjacent units on the same floor or connecting a duplex across floors, the filing requirements depend on the scope of structural and mechanical work involved.
Alt-2 vs. Alt-1: Which filing do you need?
Most apartment combinations are filed as Alteration Type 2, provided the work doesn't change the building's Certificate of Occupancy. You're combining two units into one, but the number of dwelling units in the building stays the same (the unit count decreases, but the building use and occupancy classification don't change). However, if your combination involves removing a load-bearing wall, creating a new staircase between floors, or reconfiguring the egress path, a structural filing may be required in addition to the architectural application. And if the combination changes the legal number of dwelling units in the building's C of O, you may need an Alt-1/Alt-CO filing.
What plan examiners look for
On apartment combination filings, plan examiners pay close attention to structural modifications and whether a PE-sealed structural analysis has been provided, egress compliance — particularly if the combined unit changes the path of travel to the exit, energy code compliance for the new enlarged unit, fire separation between the combined space and adjacent units, and plumbing fixture counts if bathrooms or kitchens are being relocated or removed.
Co-op and condo board requirements
In addition to DOB approval, most co-op and condo buildings require board approval before work begins. Your filing package often needs to include alteration agreements, insurance certificates, and construction schedules. Having your DOB filing prepared and submitted in parallel with your board application can save weeks on the overall timeline.
Free filing readiness assessment
→ Take the Free Filing Readiness Audit
Need help with your apartment combination filing?
Impetus Consultants specializes in Alt-2 apartment combination filings across all five boroughs. We review your drawing set before filing to catch the objection items that slow down plan examination.
Contact us: info@impetus-consultants.com | (646) 464-1675
