How to soundproof the windows in your home

Key points

• Professionals can install acoustic inserts or upgrade your glass to enhance soundproofing.

• Soundproof curtains and acoustic sealant are effective DIY options.

• Professional soundproofing methods are more effective but more costly, too.

Trains, construction and loud neighbors can increase sound transmission through your windows — disrupting your sleep, work and leisure activities. While you can’t shut down a nearby interstate to stop traffic noise and get your sleep, soundproofing your windows can help address your noise problem.

You can soundproof windows using professional or do-it-yourself (DIY) methods. Hanging sound-deadening curtains or applying acoustic caulking to plug air gaps are effective DIY options.

Installing an acoustic window insert or upgrading your window to one with double- or triple-pane glass requires professional help but can increase your window’s sound transmission class (STC) rating.

Professional window installers measure sound transmission from 0 to 100 using the STC rating scale. A higher rating translates to less noise penetration. Whichever window soundproofing method you choose, it’s imperative for your windows to create a tight seal to significantly increase their STC rating.

How do experts soundproof your windows?

Experts rely on several methods to soundproof windows including installing an acoustic-grade window insert, retrofitting your windows with laminated glass or upgrading your unit to one bearing double- or triple-pane glass.

Before we explore these further, you should have a general idea of STC ratings to better understand each method’s effectiveness at drowning out sound.

Simply put, STC 0 signifies that you would hear all external noises, as if there were no sound barrier, whereas STC 50 suggests minimal noise penetration. For every 10-point change on the STC scale, you’re achieving a 50% difference in soundproofing. For example, upgrading from STC 25 to 35 results in a 50% reduction in noise.

Attaining an STC rating of 50 is extremely difficult, as a single-pane window typically achieves only an STC rating of 22 to 24 without upgrades.

Here are common soundproofing methods used in professional installations.

Option 1: Window inserts

Soundproofing window inserts are designed to be pressed into the interior frame of your existing window, just a few inches away from the pane of glass. They can be mounted using screws, hook and loop closures or magnets for easy removal when you want to open the window.

“They can reduce outside noise by up to 80%,” said David Heim, a retired contractor with 17 years of industry experience. However, the percentage of noise reduction you achieve depends on the insert type and brand.

• Standard window inserts, which are 1/8 inch thick, can reduce noise by 50%.
• Acoustic-grade window inserts, which are 1/4 inch thick, typically block up to 70% of outdoor noise.

When placed over a single-pane window, acoustic window inserts can reduce noise by more than 70%. For double-pane windows, they can reduce noise by 50%, yielding an STC of 42 to 45, according to Indow Windows, a Portland, Oregon, company specializing in soundproofing and energy efficiency.

Window inserts may cost $372 for standard grade or $480 for performance grade, based on prices from Indow Windows. They’re available in different sizes, colors, shapes and materials.

Consider window inserts if the following criteria apply to you:

• Want to achieve an STC of 42 to 45
• Don’t mind spending more for top-tier noise reduction
• Don’t want to damage your existing window
• Live in an apartment
• Want a solution that’s easy to remove
• Want something that will fit your home’s aesthetics or enhance curb appeal

Option 2: Upgrade to a double- or triple-pane windows

By swapping out a single-pane window for a double- or triple-pane window, you can increase its STC rating from 22–24 to 27–30. A window with double glazing (or triple) features two layers of glass (or three) with a gas-filled space between them, providing enhanced insulation and noise reduction.

A professional window installer may be able to retrofit your existing window with a double or triple-pane window if the configurations of both units match. Retrofitting a window requires some expertise, so it’s a good idea to consult a professional window installer who is aware of local building codes and regulations.

If retrofitting is not an option, you can replace your windows, though this requires altering your home’s structure.

Double and triple-pane windows are priced based on frame and window type, size, brand, product location and insulating features.

At Lowe’s, dual-pane windows start at around $117 but can cost as much as $2,000. Lowe’s lists triple-pane windows from $199 to $768, with factors such as size and frame material largely dictating cost.

Consider double- or triple-pane windows if the following criteria apply to you:

• Want to achieve an STC of 27 to 30
• Have old or leaky frames and already need window replacement
• Want an invisible solution to sound transmission issues
• Want more energy efficiency in addition to significant noise reduction 
• Want to increase the value of your home

Option 3: Swap out current window glass for laminated glass

Laminated glass is made with two plies of glass sandwiched around a small flexible layer of rubber called polyvinyl butyral. This thin polymer interlayer acts as a shock absorber, reducing sound penetration. Laminated glass, often used in display cabinets, jewelry stores and aquariums, has an STC rating of about 38, making it one of the superior choices for soundproofing windows.

The cost of adding laminated glass to your current window can vary depending on factors such as the size of the window and installation expenses. For the most accurate pricing, consult with local window suppliers or professionals in your area.

Consider laminated glass if the following scenarios apply to you:

• Want to achieve an STC of about 38
• Want an invisible solution for soundproofing that doesn’t obstruct your view
• Don’t want to replace your windows
• Have window frames in good condition to support the weight of laminated glass

Option 4: Install storm windows

A storm window is an additional single-glazed window mounted on the exterior or interior of an existing window, explained Dave Martin, president of Allied Window, based in Ohio. 

The best storm windows are made from tinted, tempered or laminated glass, providing additional protection from drafts, moisture and noise. When installed with laminated glass, storm windows can achieve sound reduction of up to 80%.

The storm window’s pane type and thickness impact its ability to reduce noise. If you opt for a 1/8-inch storm window, expect an STC rating of 31 to 37. Upgrade to a 1/4-inch laminated glass, however, and the STC rating jumps to 41–45.

Added benefits of storm windows include a 50% uptick in the window’s energy efficiency and UV reduction of 99% when installed with special glazing, Martin said. They’re commonly installed over historic wood windows to protect them from rotting and damage. The downside is that the storm windows are exposed to the elements and often require regular window maintenance.

Consider storm windows if the following criteria apply to you:

• Want an STC rating of 31 to 45 (depending on the storm window’s quality)
• Want an option for retrofitting existing windows
• Want to protect window frames from damage
• Care about maintaining curb appeal
• Want enhanced energy efficiency and UV reduction in addition to soundproofing
• Don’t mind regular storm window maintenance

How do you soundproof windows yourself?

Effective DIY options to soundproof your windows include applying acoustic sealant and hanging sound-deadening curtains. Here’s what each entails.

Option 1: Apply acoustic sealant

Over time, houses move and shift, forming cracks and openings around window frames that give way to water, insects and noise. These cracks can be filled with acoustic caulking — nonflammable, latex-based sealants designed to reduce noise transmission.

Use an acoustic sealant to fill in any small gaps or cracks you notice along the frame of your window. Acoustic caulking is flexible and can adhere firmly to most building materials. If you’re dealing with more than a small crack, contact a professional for consultation and window repairs or replacement.

Acoustic sealant by itself generally ranges from $10 to $15 per tube, though you’ll need a caulking dispenser to apply it. If you don’t have one already, that can run you another $5 to $20, depending on how fancy you want to get. Allow about 48 hours to dry, following the instructions provided on the packaging.

Consider acoustic caulking if the following criteria apply to you:

• Favor affordability and convenience over more effective solutions for noise pollution
• Don’t mind making a mess during the process
• Have older, cracked windows that need a quick fix before upcoming replacement
• Want a discreet solution that’s easy to paint over

Option 2: Hang soundproof curtains

Soundproof curtains, also called sound-dampening curtains, can reduce roadside noise. They’re sold as standard or industrial grade, made from polyester alone or reinforced with vinyl.

Typically, sound-deadening curtains can attain an STC of 20, with heavier options reaching an STC of 26. Combining these curtains with a double-pane window further enhances your window’s ability to block out sound.

Sound-deadening curtains vary in price, with panels available for around $13 each on Amazon and reaching up to $200 per panel, depending on size, design and retailer. Before making a purchase, read product reviews to gauge the effectiveness of the curtains.

Consider soundproof curtains if the following criteria apply to you:

• Live in an apartment
• Have limited access to tools or want something easy to install
• Want a cost-effective sound barrier
• Don’t mind selecting from limited design options

Should you DIY or hire a professional?

Professional soundproofing methods are better at dampening unwanted noise than DIY methods are but are more costly. DIY methods using readily available soundproofing materials are easier, quicker and more affordable — but you may have to sacrifice aesthetic appeal and combine methods to achieve your desired level of noise reduction in your home.

If you consider yourself moderately handy and have only a mild sound problem, it might be worth it to exhaust DIY options first. However, investing in professional soundproofing methods may be worth it for most homeowners, as they’re more likely to yield the desired results and enhance the value of your home. Additionally, services provided by professional installers typically include a warranty, offering homeowners peace of mind.

What’s next?

As you weigh your soundproofing options, keep in mind that when upgrading your windows, vinyl and wood framing are typically more effective for noise reduction, and casement, awning and fixed windows are also known to seal tightly, which can reduce sound transmission.

While replacing windows with double- or triple-pane units may not be your first choice if your windows are new, it may be necessary if you’ve explored other options without achieving your desired level of quiet. We recommend gathering at least three quotes from reputable replacement window companies.