How Soundproof Are New NYC Condos?
Summary: Will you hear your neighbors? Every new NYC condo's offering plan describes how its walls and floors are built and often how they're rated for sound. We read the plans for buildings filed since 2021 to explain the ratings, the materials and what most buildings actually promise.
STC and IIC, in Plain English
STC (Sound Transmission Class) measures how well a wall or floor blocks airborne sound: talking, music, a TV. IIC (Impact Insulation Class) measures how well a floor-ceiling blocks impact sound: footsteps, dropped keys, a chair dragged across the floor.
Higher is better for both. As a rough rule, each 10 points cuts how loud the sound seems by about half. So STC 60 is a meaningful step up from STC 50. According to the plans, the NYC Building Code sets a minimum of 50 for both between apartments.
The catch: ratings are often measured in a lab. Real-world results in a finished apartment usually come in a few points lower, because sound also travels through gaps, outlets, ducts and pipes.
What Most New Buildings Promise
We searched the plans of the 961 new-construction NYC condos filed since 2021 that we have in searchable form. 68% of them mention an STC rating.
| STC: code minimum only (50) | 64% |
|---|---|
| STC 55 or higher | 30% |
| STC 60 or higher | 10% |
| IIC: code minimum only (50) | 85% |
| IIC 55 or higher | 7% |
Share of plans that give an STC number (388) or an IIC number (403).
Among recent plans where we could read a number, 64% promise only STC 50 (388 plans) and 85% only IIC 50 (403 plans), the code minimums. A smaller group goes further: 30% of plans that give an STC number reach STC 55 or higher for at least one wall or floor, and IIC 55 or more is rarer, in 7% of plans that give an IIC number.
- Claremont Hall uses a 5 mm acoustical underlayment under its wood and tile floors to reach IIC 55.
- The Morgan targets a lab-tested IIC 53+ with a 5 mm rubber underlayment on a 9-inch slab.
- At 156 Somers Street in Brooklyn, the walls between apartments are rated STC 55.
Floors: Why the Underlayment Matters
New NYC condos generally have concrete slab floors. Among the 300 recent plans that give a slab thickness in their sound description, 47% name an 8- or 9-inch slab and 35% a thinner 4-inch one. Concrete is heavy, so it's good at blocking voices. But it carries footsteps well. The plan for Centric in Queens spells it out: an 8-inch slab alone rates about STC 57–58 but only IIC 28–32, far below the code's 50.
That gap is closed by a thin resilient layer between the slab and your floor. Plans describe it in detail:
| Building | Floor build-up, top to bottom | Rating |
|---|---|---|
| Longfield, Flushing | Engineered oak, 5 mm Regupol Sonus underlayment, 8" concrete slab | IIC 50+ (checked by an acoustic review) |
| The Cortland, Manhattan | Finish floor, 10 mm resilient underlayment, concrete | IIC 50 |
| Northern Center, Queens | Wood or tile, Duracoustic sound underlayment, leveling compound, 9" slab | STC/IIC 50 |
| Timberburg, Brooklyn | Engineered wood, 3 mm underlayment, 3" concrete, 25 mm underlayment, mass-timber (CLT) slab | STC 55, IIC 52 |
Tip: if you plan to replace the floors, ask the board what underlayment is required. Leaving it out can put your floor below code and annoy your downstairs neighbor. Some buildings also have carpet rules: The Morgan's house rules require at least 80% of most rooms' floor area to be covered with rugs or carpet.
Walls: Layers, Insulation and Separation
Walls between apartments in new NYC condos are usually metal studs with gypsum board, not concrete. The sound rating comes from mass (more layers of board), insulation in the cavity, and how well the two sides are kept from vibrating together.
- Claremont Hall reaches STC 50 with two layers of 5/8" gypsum board on each side of a metal stud and batt insulation.
- 156 Somers Street reaches STC 55 with steel studs, spray foam insulation, and two layers of 5/8" fire-rated gypsum board on each side.
- In lighter-framed buildings, plans often list resilient channels, thin metal strips that hold the drywall slightly away from the framing so vibration doesn't pass straight through. 43 Saint Marks Place uses them under its floor assemblies.
Windows: The Third Ratings Number
Street noise comes through windows, rated by OITC (Outdoor-Indoor Transmission Class). Buildings on loud streets often have to meet a set level. At Malabar Residences, the lower floors and some facades get laminated glass rated OITC 32–33, while most upper floors get standard glass at OITC 30. The Cortland's windows are rated OITC 33.
Don't Count on a Noise Guarantee
The catch: sound performance is rarely warranted. Claremont Hall's plan says there is no warranty as to sound transmission unless it's caused by a code violation. If the building meets code, noise you don't like usually isn't a defect. See builder's warranties and punch lists.
What to Check in the Offering Plan
- The "Description of Property" section (often labeled 20.7). Look for STC, IIC, "underlayment" and "acoustic."
- Whether ratings are lab or field tested, and whether an acoustic consultant reviewed the design.
- Window OITC ratings if you're facing an avenue, highway or elevated train.
- House rules on carpet coverage and flooring changes.
Search "STC 60" or "acoustic underlayment" on The Condo Book Project, and see how condo finishes have changed.
FAQ
What STC rating is good for a condo?
STC 50 is the NYC code minimum between apartments, and most new buildings promise exactly that. STC 55 is a noticeable upgrade, and 60 or more is excellent.
What is a good IIC rating for floors?
IIC 50 is the code minimum and the most common promise. IIC 55 or higher means noticeably less footstep noise from upstairs.
Are concrete buildings soundproof?
Concrete blocks voices well, but a bare 8-inch slab rates only about IIC 28–32 for footsteps. The underlayment under the finished floor makes the difference.
Can I test the soundproofing before buying?
You can visit at a busy time, ask whether field tests were done, and ask current owners. In a new building, read the Description of Property in the offering plan.
Is noise from neighbors a construction defect?
Usually not, if the building meets code. Many plans exclude sound transmission from any warranty unless the code was violated.
Where do these figures come from?
From a search of the 961 NYC new-construction condo offering plans filed from 2021 through 2026 that have searchable text, plus the specific plans named above. Ratings are the developers' design targets. Updated October 2026.
How are the ratings counted?
STC and IIC counts use ratings of 45 and up; a plan's numbers may describe walls, slabs or full floor assemblies. Rating counts come from automated reading of plan text and are approximate.
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