STC Ratings for Windows: Best Windows for Sound Reduction

STC Ratings for Windows: Best Windows for Sound Reduction

Are you in the market for new windows or just plain fed up with your current windows that do nothing next to trapping out sound? Or, perhaps you are a homeowner in the midst of a home renovation and have heard that new windows can help increase your property’s value.
Windows for Sound Reduction

In either case, understanding what makes new windows so great, which is determined by its STC ratings, will help ensure you don’t waste time and money on cheap, hollow windows that nobody enjoys, but instead make a smart investment in quality windows that not only enhance safety and energy efficiency but that also help block out sound for a peaceful, cozier home.

To help you select the best soundproof windows for you, let’s first begin with an explanation of STC ratings, which windows have the highest STC ratings, and how the STC rating can be improved to provide some of the best soundproof windows on the market.

About STC Ratings

STC ratings, which is short for Sound Transmission Class ratings, is a measurement used to determine how proficient window glass is at blocking sound waves as tested by 18 different frequencies.

As a general rule, the higher the STC rating, the more effective the glass is at blocking out sound.

An STC rating is not just used to rate the soundproofing ability of windows, it is also used to rate the sound resistance of various materials used in your home or business, which will help you with selecting materials that contribute to a more soundproof structure.

For instance, just like most windows, both the interior doors and the walls are also often made of hollow materials that permit a significant amount of noise through and into your personal space. However, windows said to be a major, if not the major, source of noise transfer into your home.

Therefore, we will examine their STC ratings to see how they impact sound reduction, which will help you determine the best windows for you based on their STC rating.

Window Materials and How They Impact STC Ratings

Frame Materials and STC Ratings

Windows vary in glass material types as well as frames, which together ultimately impact the window’s overall STC rating.

For instance, when it comes to the frame, the sturdier and long-lasting the frame, the more it will provide a secure fit for the glass, which helps prevent the glass from shifting or sagging, which can lead to openings and gaps around the window that permit noise in, no matter how high the window’s STC rating.

There are various frame materials to choose from, including vinyl, wood, and fiberglass, and more.

Vinyl provides the window with good insulation; however, it is very fickle, depending on the temperature.

Meanwhile, wood frames are a more affordable option, which can also be used to complement the look of the property.

Windows frame for Sound Reduction

However, wood can become severely damaged over time due to water damage, which makes it also an unstable material.

On the other hand, fiberglass is a high-quality material that lasts for a long time, which just may make it the best choice when it comes to window frames; however, it is also more costly than many other frame materials.

Therefore, understanding the different frame materials in relation to your particular climate or environment will help determine the best frame for you.

Glass Materials and STC Ratings

Now let’s take a look at the different glass materials from basic, more affordable glass options to more high end specially manufactured glass options to see how they work to either improve or lower the STC rating.

1. Single-Paned Windows

Single-paned windows are the cheapest and easiest to install. However, they only have one layer of glass; therefore, their STC rating is usually very low, meaning it is very vulnerable to noise transmission.

For example, traffic traveling just outside the window can be heard clearly. Likewise, any sounds made just inside the window can also clearly be heard clearly by passersby, even while at a moderate tone.

Since single-paned windows are so hollow, they also enable energy to easily enter and escape through the window throughout the seasons, which means you may end up spending more than what the windows initially cost in energy costs.

Pros

  • Inexpensive.
  • Easy to install.
  • Can be reinforced with other window options to improve sound reduction.

Cons

  • Low STC rating between 26-28, which means it permits noise into and out of your home with ease.
  • Not energy efficient, which can lead to higher costs later.

2. Glazed Windows

Glazing the windows, also known as double-pane windows, double glazed windows, and insulating glass (IG), means installing another layer or more of glass to the window, and it is one of the best solutions for reinforcing or soundproofing single-paned windows.

Casement windows are a good example of double-pane windows because they have two or more glass window panes separated by a small insulated gap to decrease energy flow in both directions.

These windows are typically glazed using either dissimilar or laminated glass to greatly improve their STC rating for a warmer home and greater sound reduction.

Pros

  • Average STC rating of 29, but can be as high as 35 or more if a thicker glass, such as laminated glass, is used.
  • Can be used to reinforce or soundproof single-paned windows, which can reduce the sound by half, depending on the glass.
  • Increases energy efficiency.

Cons

  • Extremely energy efficient, which can make your home too toasty during the warmer months.
  • Can cost between $200 and $2,000, depending on the size and material.

3. Laminated Glass

Laminated glass, as we saw earlier, is the greatest glass material for sound reduction. However, it can also be the most costly.

The best example of laminated glass in action is with impact windows, which are most often used to help protect homes during various threats, including natural disasters.

Impact windows generally consist of two pieces of laminated glass with an inner layer of Polyvinyl Butyral, or PVB, plastic, which is most often used when various safety windows; however, it also helps improve sound reduction.

PVB plastic helps scatter sound, which, when coupled with laminated glass, further prevents sound travel in and out of a room, which makes impact windows with laminate glass the best at noise reduction.

Pros

  • Average STC rating of 35 but can be as high as 41 if a thicker PVB is used.
  • Best at noise reduction.
  • An inner layer of PVB increases the STC rating.
  • Can be used with various window options to increase the STC rating.

Cons

  • Can be the most costly choice.
  • Not as ecological as Low Emission glass.

4. Dissimilar Glass

Dissimilar glass windows have two separate glass panes that vary in degree of thickness; hence, its name.

For instance, one pane may be 3/16-inches thick, while the other pane may be 2/4-inches thick; however, their uneven thickness works together to block sound in both low and high frequencies, which provides more control over sound reduction as compared to traditional single-pane windows, and it also greatly increases the STC rating of the window.

Pros

  • An average STC rating of 34.
  • Provides comparable sound reduction effects to laminated windows but at a fraction of the cost.
  • Can be used with double-pane windows to block both high and low sound frequencies.
  • Also provides energy efficient benefits.

Cons

  • It’s STC rating is not as high as laminated glass.

5. Three-Paned Windows

Three-pained windows contain three layers of glass and a small air space in between.

However, because the glass is of equal thickness, and they have a smaller than average air space in between, they offer the same level of noise reduction as double pane windows, contrary to the common belief that more glass equals more sound protection than single or double pane windows.

Pros

  • Has an STC rating comparable to standard double pane windows.
  • Highest energy efficiency.
  • Increases home’s safety.

Cons

  • The 3 layers of glass offer no more sound protection than single or standard double pane windows.
  • Since they have smaller than average air spaces in between, the air spaces can sometimes magnify noise, making the problem worse.
  • More costly than double-pane windows but with comparable results.

For the best STC rating possible, the windows should be installed by an experienced professional who will ensure the windows are the right dimensions for the current openings and who will also install the windows properly.

In the meantime, remember the frame material also plays an important role in the STC rating; therefore, be sure to have the existing frame checked and replaced, if needed, to ensure the new windows live up to their desired performance. In fact, with the right combination of factors, it is possible to increase the STC rating of glass as high as 46 for some of the best soundproof windows available just short of airport windows.

Conclusion

As you can see, choosing the best soundproof windows is an art; however, hopefully, this short guide has made it much easier to understand the different window materials and how they can impact a window’s sound transmission, or STC rating, especially when combined with other glass or insulated materials.

For the best overall soundproof windows, laminated windows are said to be the best. In fact, they have the highest STC rating of all glass types at a 35 rating, which can even be increased by adding a layer of PVB plastic to the inner space of the window to help disperse sound for a superior STC rating in the 40s. However, they are also the most costly choice.

Therefore, for a more budget-friendly choice, I would recommend investing in dissimilar glass windows, which deflect both high and low-frequency sounds, thus providing an STC rating of 34, just short of laminated windows rating of 35; however, they cost a fraction of the price.

In the end, just be sure to check out the various windows listed to find the best ones for you. However, whatever you do, you might want to avoid basic single-pane window’s, which while they may be the cheapest option, also have the lowest STC rating, sometimes even falling below a 20 rating, meaning they offer very little to no sound protection and can also rack up energy costs. Instead, stick with more superior windows with an average STC rating of 32 or more to ensure you get your money’s worth.

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