STC Rated Windows For Your House

Like most things in the window business stc rated windows or sound transmission class windows are often misunderstood or misrepresented by salespeople.  We’ve heard all sorts of stories and explanations regarding sound control windows.  The truth rarely gets out there, but here we will cut through the fluff to explain how the various options will work for you.  We’ll look at what these ratings mean, where you will get the best bang for your buck and common mistakes people make when trying to keep their home quiet.

There are standard stc rated windows that can increase the efficiency of your home with specific options and then there are specially designed stc rated windows that are designed for very high noise applications around airports, railroad tracks, or busy city centers.

We’ll start with typical replacement windows.

It is very common to hear a salesperson tell a customer that triple pane windows are a great way to reduce sound transmission.  That seems plausible as 3 panes of glass would likely be better than 2, but in fact it is not the case.  Triple pane windows have smaller air chambers than double pane windows and they sometimes use thinner glass as well to reduce the weight.  As a result, triple pane windows will sometimes be worse than a typical double pane unit and will almost never be better.

An easy way to get a better stc rated window is to add dissimilar glass.  This means one pane of glass is thicker than the other.  A common way to accomplish this is to use laminated glass.  Laminated glass is like the windshield of your car.  It’s actually 2 pieces of glass with a piece of plastic in the middle.  In a double pane window like this, one of the panes will be thick because it’s laminated and the other pane will be thinner because it’s not.

This is typically the best way to take a regular residential replacement window and make it a better stc rated window.  The rating will increase by up to 20% using this method.

So what do these ratings mean?

It’s always hard for folks to get their head around what does a rating of 27 mean or if another product has a rating of 33 how much better is that?  One way to visualize this is to consider that a typical exterior wall with siding on the outside drywall on the inside will have a rating around 34.  A wall with brick instead of siding will be a bit better.

Imagine being in a room with no windows, say a closet in your bedroom.  If a firetruck pulled up outside with it’s sirens blaring you’d still hear it.  Double pane windows are better than single pane windows, and double pane windows with laminated glass will be better than that, but none of these options are sound proof.

Are there better options?

Yes, there are better stc rated windows, but when you go too extreme the windows start to look a little unusual.  This isn’t really an issue if you like on the side of the highway or the approach path to O’Hare, but if you’re just trying to block out the noise of those pesky kids next door you might want to weigh your options.  The Quiet Line from Milgard.  It uses 2 sashes to provide an extra layer of sound insulation. 

stc rated windows
Notice how this window has 2 bottom sashes. It achieves excellent stc ratings, but the sacrifice is that it is a relatively unusual configuration.

What are the common mistakes people make when trying to keep their home quiet?

The number one mistake we see folks make is to install fancy new triple pane windows in an effort to reduce the sound transmission.  As discussed above that is typically a waste of money.

The other common mistake is to think that after installing new windows their home will be completely silent.  The fact is that’s just not the case.  New stc rated windows can make a substantial improvement in the efficiency of the home, but sound is getting in through your walls, your ceiling and your floor.  Depending on how your home is built, there may not be an easy way to completely block out those pesky kids next door after all.




20 thoughts on “STC Rated Windows For Your House”

    1. It should be the higher. The higher the STC value, the better the sound reduction properties of the Window.

  1. Hey ‘Dog,

    A few things.

    One, you say Triple is not better than Double. The mitigating factor would be Offset Technology. It zooms past Double. By compacting the Krypton to 1/4″, you open the Argon chamber to 1/2″ for maximum sound & energy performance.

    You lump dissimilar glass thickness with laminated. These are distinct factors in sound mitigation. Dissimilar glass thickness adds ONE dB and laminated can add up to FOUR dB.

    Other factors such as insulated frames, type of insulated frames and Style of window e.g. Euro-style Tilt & Turn with double gaskets is dramatically better at sound attenuation that a double hung.

    Best, Jim

    1. Of course you’re right. The trick is that most common residential window manufactures don’t offer several of those options. It would be great if they did. Which manufacturers would you recommend to someone looking for those options?

      1. With that said. Which is the better of these 2 options for the Alside Mezzo Window.
        Option 1: 2 Panes of Double Strength Glass with Clima Tech Therm D IE windows which I believe is 1/4″ Laminated Glass on the Outside, a 3/8 ” Center Thermal Barrier and 1/8″ inside Glass
        Option 2: Triple Pane (TG2) which is 1/8″ Glass on the outside, 3/8″ Thermal Barrier, 1/8″ Middle Glass, another 3/8 Thermal Barrier and then 1/8″ Glass for the inside.
        It seems the Triple Pane would be better due to the 2 airgaps. Or am I wrong? Thanks for the reply.

        1. From a sound transmission standpoint, the laminated glass will be the best option. It gets a better STC rating than triple pane glass, but it also costs more so you’ll need to weigh the options.

  2. Hi,

    You mention living near highway or Ohare doesn’t matter. Are you saying the double pane laminated vs unlaminated won’t make a difference with LOUD noise, so just save your money and get a double unlaminated?


    1. Laminated glass makes a pretty big difference with noise. You can see that in the STC ratings, no need to guess.

      1. Hi there Windowdog

        Do you know of a good quality brand of windows that has double-pane with dissimilar glass thickness where one pane is laminated and the other is not AND that have double sashes? I’m trying to find the highest STC rated window built specifically for noise blocking if there is such a thing. I read somewhere that Jeld- Wen has some vinyl models with dissimilar glass but can’t find information about them or whether they are also laminated or not. I prefer the dissimilar glass with lamination if they exist – but it’s a little like chasing unicorns

        1. Well, to my knowledge just about all double pane windows with laminated glass will have dissimilar glass thicknesses. The laminated piece is pretty thick (the exact thickness varies based on what the manufacturer has available) and the other pane is not laminated.

          You may have a harder time finding windows with double sashes meaning you have to open the inside sash and then the outside sash to get to the fresh air. Years ago I ran a window distributor in Springfield, VA and some salesperson brought in a window just like that. He wanted us to carry it and we never did. Unfortunately I can’t remember the brand.

          One piece of advice would be to focus on the STC rating so you’re looking at the results rather than the methods. Ultimately, what does it matter if they have this glass or that glass? What matters is how well the window blocks the sound and you can see that in the STC rating. Good luck!

  3. Hey folks, almost every window manufacturer (and they are about 1000 of these in the U.S., can “special order” (and, typically, all orders are special ordered anyway) a 1/8” pane over a laminated glass pane and you will get incredible results (no matter what brand of window). Every manufacturer can special order their glass units for you. You just have to weigh out the difference in cost and ask what the STC ratings.
    So, choose any window company in your area that is in the top 10 brands listed, and you will be fine. STC rating’s above 43 are fantastic. By the the way, you can order a 1/8” pane with a 3/16” pane and you will have incredible results and it’s very, very inexpensive to do that. Again, 1/8” which they call double strength, over a 3/16” double pane unit (insulated glass unit) with as wide of an airspace between panes (seal) as possible, typically 3/4” OA (“over-all”) or a 7/8” OA and you will have an incredible STC rating with this. You will spend much, much less than laminated glass would cost. And that’s it.

    1. That is the best explanation I have seen on the very important topic.

      Can I please ask what do think of these options.

      It seems the Triple Pane would be better due to the 2 airgaps. Would appreciate your opinion. Thanks

      1. Hi Randy, the Alside Climatech ThermD iE package does not include laminated glass. Laminated glass is available, but it costs a fair bit more than regular annealed glass. As far as which option is better the triple pane is more expensive and more efficient. Only you can decide if the increase in efficiency is worth the increase in cost.

        Luckily you you don’t need to guess as to the effectiveness of any options like that. Just look at the efficiency ratings and you can see what the difference is. In round numbers triple pane glass tends to improve the efficiency by around 25%. Laminated glass doesn’t help with efficiency, but it does help with both sound and security.

        Which one fit you pick?

  4. Is an STC rating of 35 good to block highway sound near by? Looking at the Milgard styleline 1/4 over 3/16. Is it advisable to increase STC to 38 or higher by going to laminated glass?

    1. Blocking sound can be tricky. What one person might consider to be pretty quite may be completely unacceptable to someone else. If you are trying to block highway noise I would go as high as you can and then consider that some sound is coming through the walls and the ceiling. It’s not all coming through the windows. An STC of 38 is pretty good for most residential windows.

  5. TheWindowDog,
    I’m on the hunt for replacement windows with as high of an STC rating as possible. I’m open to double sash but prefer to stick with a regular casement type window. Current windows are builder grade jeldwen double panes. Home is 4 years old and when I moved in a year ago I discovered cracks and gaps around all windows. In some cases 3/8” gaps under the sill. I’m assuming it’s possibly from a bad installation but I don’t know much about windows. I’m under a flight path and am looking for reduction in noise. Currently have window plugs (made from 1/2” mdf) in master bedroom, which make a big difference, but would prefer to upgrade the windows.


    1. Typically a window with laminated glass will give you the best STC rating in a normal residential type window. Remember if it’s airplane noise you’re concerned about most of that noise is probably coming through the roof and ceiling. Insulation in the attic may be more effective.

  6. Hi, can you please give me your thoughts on Simonton Vinyl window series 7300 Daylight Max? Single-hung.

    I live on a busy street with lots of cars, trucks, train horn occasionally and I am a light sleeper. I am going retro fit. A window company recommended this because the frame is slimmer. I live in a townhome that has a HOA.

    Should I go with dissimilar glass or laminate, or both is there is such a thing as both?

    The spec on my current windows are-Ply Gem window, double pane with a STC of 28 I think. Series: insulate 400. CPD: PWG-M-125. NFRC 100/200. Complies with HUD UM11.

    I tried looking at Milgard but the frame is too thick. Can you recommend any other windows to help with my issues here?

    Thanks a billion for your help.

    Thank you,
    Wai See

    From Newwark CA

    1. Hi Wai, I’d look at the STC ratings of the various options to compare. Laminated glass will always be of dissimilar thickness because one piece will be laminated and the other will not. It’s more expensive than regular annealed glass, but will likely perform better in terms of sound reduction.

      You’ll want to keep in mind that there is sound getting through the walls and the ceiling as well. In the past we’ve had customers order new windows with laminated glass and still not be thrilled with the results. The windows performed as expected, but the customer was hoping the new windows would eliminate all sound and that’s just not how it works.

      Imagine if there were no windows at all and a fire truck outside, you’d still hear the siren. Just something to keep in mind. The STC ratings of any options compared with the cost would be where I would start.

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