Laminated glass, unequal lites, dual-layer windows and secondary interior windows — the five steps that make a New York room quiet, in the order they work, with honest numbers and the reason triple pane is not the answer to noise.
Short version. No window is soundproof, but the right one makes a bedroom over the BQE quiet enough to sleep in. What works, in order: fix the seals; put laminated glass in the unit; make the two lites different thicknesses; and, where the noise is serious, add a second window inside the first. What does not work as well as the ads say: triple pane. It is a heat product, not a noise product. Here is how to choose, and what it costs to get wrong.
Sound reaches a room through three routes, and the window you buy only fixes one of them. It leaks around the frame — a worn weatherstrip, a loose sash, a gap behind the trim. It passes through the glass, which vibrates like a drum skin and re-radiates the noise inside. And it comes through everything next to the window: the through-wall air conditioner sleeve, the vent, the thin spandrel panel under the sill. On a Brooklyn apartment the sleeve is often the loudest path in the room, and a new window will not touch it. That is why we measure with a meter on site before recommending glass: the money has to go where the sound comes in.
| Step | What it does | How much quieter | Cost |
|---|---|---|---|
| 1. Seal the window | Closes the gaps around the sash and frame that let sound straight through | Often the biggest single gain on an old window | Lowest — sometimes a service call, not a replacement |
| 2. Laminated glass | A plastic interlayer between two lites damps the vibration instead of passing it on | +3 to +6 STC points over plain glass of the same thickness | Moderate: a laminated insulated unit in the existing frame, or a new window with one |
| 3. Unequal lites | Two different thicknesses resonate at different frequencies, so no single pitch gets through both | +2 to +3 STC on top of laminated | Small — a specification choice |
| 4. A dual-layer window | Two insulated units in one deep frame, factory made (Crystal AC85 and similar) | STC 42–57 depending on the glass | Higher: a full replacement window |
| 5. A second window inside | A separate interior window a few inches behind the existing one, with a deep air space | +10 to +20 STC; the strongest option there is | Highest, but leaves the original window in place — the landmark answer |
Windows are rated STC (for speech-range noise) and OITC (for the lower-pitched traffic, aircraft and rail noise that New York actually makes). A standard insulated window is about STC 31–33; a laminated one 35–38; a dual-layer or secondary window 45 and up. Every 10 points is roughly half as loud to the ear. Ask for the OITC too, because low frequencies pass through glass more easily than speech and the STC figure flatters the result: the Crystal AC85 placard, for instance, shows STC 42–57 against OITC 36–46 for the same five glass make-ups. And the rating is for the glass in a lab frame — the installed result depends on the frame, the seal and the wall, which is why the first step on the list is the first step.
Triple glazing is sold hard in Brooklyn right now, usually with a heat-retention figure and the word “soundproof” nearby. Thermally it is real: three lites and two argon spaces cut heat loss well. Acoustically it disappoints, because three equal lites with narrow air spaces resonate together, and the extra pane adds weight without adding damping. A double unit with one laminated lite and unequal thicknesses is usually quieter than a triple, at less weight and less cost. If you need both — a cold, loud apartment — the answer is a laminated lite inside a triple, or a dual-layer window, not a triple on its own. Our laminated vs triple pane for soundproofing comparison goes through the numbers.
Laminated insulated units in the existing frame. The least disruptive upgrade when the frame is sound: a tempered exterior lite over a laminated interior lite of a different thickness, argon-filled, replacing the glass only. Right for an avenue with bus traffic, a school yard, a bar two floors down.
Dual-layer acoustic windows. Two insulated units in one deep frame, made as one window — the Crystal AC85 is the one we specify most. Right for apartment buildings and houses where the existing frame is part of the problem.
Secondary interior windows. A second frame fitted inside the reveal, three to six inches behind the original, which stays. The largest reduction available and the only route on a landmarked facade where the street-side window cannot change; the 1763 Amsterdam Avenue church window is this, built from two lites of half-inch laminated glass across a three-inch space.
The BQE corridor through Carroll Gardens, Cobble Hill, Williamsburg and Greenpoint; the Belt Parkway along Bay Ridge, Bensonhurst and Sheepshead Bay; the Gowanus Expressway over Sunset Park; the LaGuardia and JFK approaches over Astoria, Jackson Heights, Howard Beach and the Rockaways; the elevated lines on Brighton Beach Avenue, New Utrecht Avenue and Broadway in Bushwick; the FDR and the West Side Highway in Manhattan; and the ordinary avenue with a bus route and a nightlife strip. We have worked on most of them. Tell us the block and we will know the noise before we visit.
A laminated glass-only upgrade in an existing frame is the least expensive path; a dual-layer replacement window costs more than a standard window of the same size, roughly in line with a premium European unit; a secondary interior window is priced per opening and depends on the reveal depth and the glass. We quote from a site visit with a meter reading, so the proposal says what the noise is now and what it should be after. Co-ops: the alteration agreement usually covers this as a window replacement; we handle the paperwork. See window replacement in Brooklyn for how a job runs, and acoustic glass for the technical detail behind everything on this page.
No window blocks all sound, but the right make-up cuts it dramatically. A standard window is about STC 31–33; a laminated one 35–38; a dual-layer or secondary interior window 45 and up. Every 10 points sounds roughly half as loud.
Less than people expect. Three equal lites resonate together; a double unit with one laminated lite of a different thickness is usually quieter, lighter and cheaper. Triple glazing is a heat product first.
For a busy avenue, a laminated insulated unit; for the BQE, Belt Parkway or a flight path, a dual-layer window such as the Crystal AC85 or a secondary interior window. We measure on site before recommending.
Often, yes: reseal the frame and replace the glass with a laminated insulated unit in the existing frame, or add a secondary interior window behind it. Both leave the original window in place.
A separate interior window fitted a few inches inside the existing one. The deep air space between them gives the largest noise reduction available and it is the standard answer on landmarked facades.
No. A through-wall sleeve, a vent or a thin wall panel can pass more noise than the window. We check these with a meter before quoting so the money goes where the sound comes in.
Yes; it is a window replacement under the alteration agreement, and we supply the specification and insurance the board requires.
Triple pane windows: are they worth it in NYC? · Acoustic Glass (technical) Laminated vs Triple Pane for Soundproofing Laminated Glass Crystal AC85 Acoustic Window Window Replacement in Brooklyn 1763 Amsterdam Avenue Church Window Glazing Glossary
About this page. Written by Alex GC Inc. d/b/a Alex Glass Construction and reviewed before publication by Aleksandr Chernovolenko, Managing Partner, with our design and estimating lead and a field foreman. Our foremen hold the NYC DOB Site Safety Training supervisor card and our crews the 40-hour worker card; we are certified to fabricate, install and service Alutech and Everest aluminum systems. Facts are drawn from our own projects, manufacturer test data and the applicable codes; where we are giving an opinion, we say so. Last reviewed September 2026. Credentials
Tell us the block and what you hear. We will come with a meter, tell you where the sound is getting in, and quote the option that fits — glass only, a dual-layer window or a secondary window.
