What is the 2026 cost range for a interior conversion scope adu in New York City?

$148,500-$313,500, with the median landing near $231,000. The range reflects finish tier and layout complexity within the interior conversion scope; the New York City labor multiplier of 1.65× vs national median is baked in.

How long does a interior conversion scope adu take in New York City?

14-20 weeks of on-site construction for the interior conversion scope, plus 10-22 weeks of permit review in New York City if the scope requires a permit. Cosmetic-only refreshes often skip permits; anything touching plumbing, electrical, or structural does not.

What is the single biggest budget-overrun risk for this scope?

Existing slab without a vapor barrier — vapor-pressure moisture leads to flooring failure and mold if not re-poured or sealed. Adds $4-8K.

ADU — Interior conversion Cost in New York City, 2026

Low

$149K

$148,500

Median

$231K

$231,000

High

$314K

$313,500

Scope timeline: 14-20 weeksNew York City permit window: 10-22 weeksUpdated 2026-04-24

Why interior conversion × New York City produces this band

A interior conversion scope for a adu in New York City combines two price levers: scope and metro labor rates. Interior-conversion ADUs repurpose an existing enclosed space (attached garage, basement) without adding foundation or framing footprint. Faster and cheaper than a detached build. Against the national median remodel labor rate, New York City runs 65% above the national median — so the interior conversion band comes in 50% below the mid-range, then scales 65% above the national median on top of that. Permit timelines for residential work in New York City typically run 10-22 weeks, which is the window you plan your design and decision sequence against. This page gives you the actual 2026 New York City bands for this exact combination, plus the three cost drivers Baily asks about first when scoping the project live.

What drives cost for a interior conversion scope

·Insulation and conditioned-space HVAC tie-in
·Egress window cutting and well install
·Kitchen and bath rough-ins (often net-new to the space)
·Legal separation from the primary unit

What makes New York City different

Labor — NYC DOB-licensed general contractors and plumbers carry the highest hourly rates in the U.S. (roughly 1.8× national median).
Labor — Union jurisdiction is strict — electrical work in most five-borough multi-family requires Local 3 IBEW.
Labor — Hoisting and delivery logistics add labor time on everything delivered above the 5th floor.
Material — Cabinet and stone slab delivery into Manhattan often requires after-hours crane crews — 15-25% uplift vs suburb.
Material — Dumpster and construction-debris permits are metered daily.

New York City rules that affect this scope

NYC DOB requires a Registered Design Professional (RA or PE) on permit submissions for most kitchen and bath work.
Co-op and condo alteration agreements typically require a 12-18% owner contribution for building-wide risk (separate from the NYC permit).
Local Law 152 gas-piping inspections affect any remodel touching gas lines.
Pre-war rent-stabilized units have separate tenant-protection filings that add 3-8 weeks to the alteration path.

Scope your adu with Baily.

Baily asks the eight questions that determine where your project lands inside the $149K-$314K band for New York City and hands the scoped brief to one licensed builder.

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Questions LA homeowners actually ask

$148,500-$313,500, with the median landing near $231,000. The range reflects finish tier and layout complexity within the interior conversion scope; the New York City labor multiplier of 1.65× vs national median is baked in.