Soundproof Window Inserts

Interior acoustic inserts. A laminated-glass pane in a gasketed or framed mount, set inside the existing window opening with an airspace of about 2 to 4 inches. Nothing is removed from the window you have, and the insert can come out for cleaning. This is the strongest of the options on this page.

Acoustic laminated glass in your existing windows. When the frames and sashes are sound and can carry the weight, the insulated glass unit is replaced with an acoustic laminated one and the rest of the window stays. Our acoustic glass replacement page covers when this works and when it does not.

Replacement windows with acoustic glass. If the windows are failing anyway, acoustic laminated glass is specified in the new unit, with unequal pane thicknesses and an acoustic interlayer, and the opening is sealed to match.

Sealing and flanking fixes. A window can leak sound around the sash and through the perimeter as well as through the glass: worn weatherstripping, open caulk joints, loose or worn hardware that no longer pulls the sash tight. Fixing those is often the first step, and it is the same work as our hardware upgrades service.

Doors, as a flanking path. A gapped or hollow door on the noisy side can undo much of a window upgrade, because sound takes the weakest route into the room. We check door seals and thresholds as part of the sound path. A rated acoustic door is a different product and is not what this page is about.

Airspace decoupling. Sound reaches a single piece of glass as vibration and re-radiates from its inner face. Two panes with a real gap between them, not touching except through the frames, pass much less. An insert adds that gap, and a 2 to 4 inch gap is far deeper than the narrow airspace sealed inside a standard double-pane unit.

The perimeter seal. A hairline gap around the edge is a hole for sound, so the insert is built to seal against the window stop all the way around, either with a compressible gasket or with a framed mount and acoustic sealant. This is why a precise measurement matters more than any other step.

Why mid and high frequencies drop more than rumble. Heavier, stiffer glass and a deeper gap help most in the middle and upper frequencies, so voices, tire hiss and sirens fall furthest. Low-frequency rumble from trucks and trains is harder to stop, because it carries through mass and structure. A deep airspace helps most with low-frequency rumble; our STC ratings guide (linked under Further reading) explains why.

These are typical STC ranges for the window assembly, and they are not a promise for a particular house. Single-pane glass is typically STC 26 to 28. A standard double-pane window is typically STC 28 to 32. A laminated insulated unit with standard PVB is typically STC 32 to 35. An acoustic-PVB laminated unit with unequal pane thicknesses is typically STC 35 to 40. A laminated-glass interior insert with a 2 to 4 inch airspace over a double-pane window is about STC 40 to 48, which is the range manufacturers publish for such assemblies.

Each 10 STC points sounds about half as loud. STC is defined in ASTM E413 and is a laboratory figure for the window, measured without the walls, doors and roof around it. In a house the result also depends on how well the insert seals, how much of the wall is glass, and what other paths the sound has. That is why we talk about a range and why we do not promise a figure.

Road, rail and aircraft noise are different problems. Highway traffic along Routes 3, 4, 17, 46, 80, 21 and 280, the Garden State Parkway and the Turnpike is steady and broadband. NJ Transit lines and the freight lines through North Jersey bring short, loud events with strong low-frequency content. Aircraft on the Teterboro and Newark approaches add low-frequency noise as they pass overhead. The same insert does a better job on some of these than others, which is why we ask what the noise is before we recommend anything.

Our guide to highway, train and plane noise in North Jersey sets out which fixes suit which source, why a highway sound wall does little for an upstairs bedroom, and the status of the Teterboro sound-insulation program. Start with the bedrooms that face the noise.

These are whole-job ranges for typical North Jersey homes. A typical job for one bedroom (2 to 3 windows) runs $1,200 to $4,000. One noise-facing side of the house (4 to 6 windows) runs $2,500 to $8,000. The whole house (10 to 12 windows) runs $5,500 to $15,000. Your quote is the number that counts: the ranges are here so you can tell whether an estimate is in the right neighborhood.

What moves a job within its range: the size of the openings, the glass specification, the depth of the window stop (the ledge an insert seats against must be deep enough for the airspace you want), and how many sides of the house you treat. For comparison, acoustic glass swapped into existing frames on 4 to 6 windows typically runs $2,000 to $6,000, and glass-only replacement typically runs 30 to 50% of the cost of a new window. Adding laminated glass to a standard replacement job runs about $2,000 to $5,500 more on 10 to 12 vinyl windows, on top of the $7,000 to $18,000 that job costs without it.

Quotes are free, usually by phone, and in person for bigger jobs. Tell us the rooms, the noise source and the window type, and we will say which option fits before anything is measured.

There are two kinds of insert, and the difference matters for performance. Compression-fit panels are a single laminated or acrylic pane edged with a compressible gasket that presses into the opening with no fasteners. They are quick to fit and come out in seconds for cleaning. Acrylic is much lighter than glass, so glass-based panels are the usual choice when the problem is rumble and a stronger result is wanted.

Framed laminated-glass inserts hold laminated glass in a rigid frame fastened to the jamb, which allows a heavier pane and a deeper airspace, and gives a firm seal with acoustic sealant. The frame is visible from inside and is available in finishes to match the trim. Framed inserts usually cost more and suit the loudest locations. We recommend one or the other after we have seen the opening and heard what the noise is.