Can You Combine Two Condo Units in NYC?

Combining two condo units in NYC? Learn how to assess feasibility, approvals, and construction timelines with this expert design-build guide.

[#1]Can You Combine Two Condo Units in NYC?[#1]

Yes — and it's one of the smartest moves available to NYC homeowners who need more space but don't want to leave the building or neighborhood they love. When one condo isn't enough, combining two units provides an opportunity to maximize square footage with a custom floor plan tailored to your lifestyle, and in the process, meaningfully increase your investment value.

That said, condo combinations in NYC are far from simple. They involve complex regulations, multiple city agency filings, condo board approvals, and construction challenges unique to New York City's built environment. Whether you own an adjacent unit already or are considering purchasing one with the intention to combine, this guide walks through the entire process — from initial feasibility through final permit close-out.

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About Gallery KBNY

Gallery KBNY is an award-winning, full-service design-build firm specializing in the architecture, interior design, and renovation of apartments, co-ops, condominiums, townhomes, and lofts across Manhattan and Brooklyn. Our integrated team of architects, designers, contractors, and project managers — with a founding partner involved in every project — manages every phase from board approvals and DOB permitting through design and construction. Because architecture, design, permitting, and construction are coordinated under one roof, the process remains streamlined, accountable, and transparent from start to finish. Our work has been recognized by Forbes, The New York Times, Architectural Digest, and Inc., and we have received Houzz Best of Design & Service seven consecutive years, along with 100+ five-star client reviews.

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[#2]Assessing Feasibility: Can Your Units Actually Be Combined?[#2]

Before any plans are drawn or conversations with your board begin, the first step is determining whether combining your two condo units is actually feasible — structurally, legally, and within the rules of your specific building.

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Pre-Purchase Assessment

We conduct pre-purchase renovation assessments for buyers during the contract period. Walk the apartment with us before you commit — understand the full scope, cost, and timeline before closing.

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Topic	Key Detail
Where asbestos is typically found	Behind walls — pipe insulation, steam risers, branch heating lines
Surface test results	Often negative on walls and floors — hidden asbestos requires invasive investigation
Required NYC testing	ACP-5 clearance certificate required before DOB permit filing
ACP-5 testing cost	$1,500–$4,000 depending on scope and number of samples
Abatement cost — typical scope	$3,000–$15,000+ depending on linear footage and materials
Abatement cost — extensive scope	$15,000–$40,000+ for full riser or branch line replacement
Timeline impact — proactive planning	Minimal — when abatement is scoped and contracted in pre-construction
Timeline impact — reactive discovery	2–6 weeks of unexpected delay mid-construction
Buildings most affected	Pre-war co-ops built before 1940; especially those with original steam heat

Topic

Key Detail

Where asbestos is typically found

Behind walls — pipe insulation, steam risers, branch heating lines

Surface test results

Often negative on walls and floors — hidden asbestos requires invasive investigation

Required NYC testing

ACP-5 clearance certificate required before DOB permit filing

ACP-5 testing cost

$1,500–$4,000 depending on scope and number of samples

Abatement cost — typical scope

$3,000–$15,000+ depending on linear footage and materials

Abatement cost — extensive scope

$15,000–$40,000+ for full riser or branch line replacement

Timeline impact — proactive planning

Minimal — when abatement is scoped and contracted in pre-construction

Timeline impact — reactive discovery

2–6 weeks of unexpected delay mid-construction

Buildings most affected

Pre-war co-ops built before 1940; especially those with original steam heat

Can You Combine Two Condo Units in NYC?

TABLE OF CONTENTS

[#1]Can You Combine Two Condo Units in NYC?[#1]

[#2]Assessing Feasibility: Can Your Units Actually Be Combined?[#2]

let’s

Design-Build

together

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View Blog In Full

Can You Combine Two Condo Units in NYC?

TABLE OF CONTENTS

[#1]Can You Combine Two Condo Units in NYC?[#1]

[#2]Assessing Feasibility: Can Your Units Actually Be Combined?[#2]

let’s

Design-Build

together

RELATED POSTS

How to Get Co-op Renovation Approval in Manhattan Without Wasting Time

How to Choose a Renovation Contractor on the Upper East Side: The 2026 Guide for Co-op, Condo & Townhouse Owners