Sound attenuation question in replacement windows

sippelmcNovember 24, 2013

Hi all,

I'm buying replacement windows (double hung) for my apartment, which face a busy street. It's a medium sized installation with two double hungs on each side of a 3 foot picture window panel. The current windows are 20+ yrs old and they are really bad in terms of giving me a peaceful room from the traffic, sirens, horns, etc.

I've narrowed things down to two quotes on different style windows dbl pane windows:

(1) has an IGU of 7/8" total consisting of 1/4" laminated glass, 3/8" air space, 1/4" laminated glass.
(2) has an IGU of 1.25" consisting of 1/8" lami, 1" air space, and 1/8" lami. [thicker frame, more cost]

Which will one will give me better sound attenuation from traffic noises? I'm torn b/c one has the thicker laminated glass panes, but while the second has thinner glass there is almost double the dead air space. Or will they basically be close to the same STC/OITC for attenuation and I should go with other factors like price, etc? Assume both are triple weather stripped and otherwise air-tight.

I can't do a second interior window like a Citiquiet or anything due to my blinds and design of the room. I'm also stuck with double hung since that is my condo's required style....

Any thoughts would be greatly appreciated...thanks!

This post was edited by sippelmc on Sun, Nov 24, 13 at 12:42

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PRO
Windows on Washington

Are you sure about the overall glass size on option 1?

.25 + .75 + .25 does not equal .875

The thicker laminate should be better but as you mentioned the deeper air space is also preferable.

Have you compared air leakage numbers on the windows as well?

    Bookmark   November 24, 2013 at 10:33AM
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sippelmc

Thanks for catching that, it was a typo (putting in 4 for the denominator instead of 8). It should be 3/8 of air space and I fixed it above.

I'm told that there wont be any air leakage for the new windows. I'm told there will be no draft as they'll have triple weather stripping. My current windows have significant leakage. For example, today is a cold day and if I put my hand up to the window I can feel a draft coming through the various places where there are seams/mechanisms.

So it seems like its almost a toss up between thicker glass / lami vs more air space, and I should move past sound attenuation (my primary concern) and focus on price and other factors? I'm pretty frustrated with dealing with people as no one wants to make any claims as to what levels of noise reduction I will get (when they come and do the estimate). In any event, thanks for the response!

This post was edited by sippelmc on Sun, Nov 24, 13 at 12:50

    Bookmark   November 24, 2013 at 12:48PM
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millworkman

There is absolutely no way to know how much sound exactly will be reduced as windows are only part of the equation.

    Bookmark   November 24, 2013 at 1:16PM
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toddinmn

Do they have any stc ratings for the windows you are looking at?
My guess is they would be pretty close. The performance would also depend on other things besides glass and air space such as spacers, air leakage, frame material, ect.
I would always take price and quality of window and installation into factor as they are just as important.
I would consider storm windows as an option as well, either over existing windows(if they are a salvageable) or on new windows if applicable(voids warranties on vinyl windows and some modern wood windows are not made to receive them.)

It would be difficult for someone to estimate what the sound reduction would would be since it would depend other factors such as the wall it is set into, how well that wall is sealed, what the wall is made of, the condition of the wall, penetrations into the wall ect. than we could look at the roof. It would be very much like trying to tell you how much energy you would be saving with new windows, not to mention you are only replacing some of windows which would make it even more difficult.
What are the 2 brands and model of windows you are considering and how much are they?

    Bookmark   November 24, 2013 at 1:52PM
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toddinmn

Do they have any stc ratings for the windows you are looking at?
My guess is they would be pretty close. The performance would also depend on other things besides glass and air space such as spacers, air leakage, frame material, ect.
I would always take price and quality of window and installation into factor as they are just as important.
I would consider storm windows as an option as well, either over existing windows(if they are a salvageable) or on new windows if applicable(voids warranties on vinyl windows and some modern wood windows are not made to receive them.)

It would be difficult for someone to estimate what the sound reduction would would be since it would depend other factors such as the wall it is set into, how well that wall is sealed, what the wall is made of, the condition of the wall, penetrations into the wall ect. than we could look at the roof. It would be very much like trying to tell you how much energy you would be saving with new windows, not to mention you are only replacing some of windows which would make it even more difficult.
What are the 2 brands and model of windows you are considering and how much are they?

    Bookmark   November 24, 2013 at 1:53PM
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PRO
Windows on Washington

Bueller....Bueller.

+1 to the previous comments.

I am not sure that 1/4 laminate on both lites is really a benefit in this application.

Do they have any STC/OITC numbers based on that glass set up?

    Bookmark   November 24, 2013 at 2:29PM
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sippelmc

Thanks.

The one's I am looking at right now are:

Option 1
http://www.crystalwindows.com/HF-Series2000A.html#anchor1

Option 2
http://www.skylinewindows.com/doublehung-series100.php [these are custom mfg'd]

I don't have an STC for either option.

I live in a coop/condo in Manhattan and the entire sill will be redone with a new aluminum installation, so the windows aren't being put in piecemeal or anything. The entire old installation will be removed and new one put in. The surrounding wall is concrete and brick. I have no options on additional outside windows as this is a high rise with strict rules on window uniformity. As mentioned above, it is possible to fit in an interior second window but aesthetically I'm trying to avoid that for now.

I'm still trying to figure out if I can go to a 4.25 inch frame (I currently have 3.25). If not, it takes out the skyline window. It will fit in the sill but unless the snaptrim is pushed in it will ruin the blinds installation (which are up/downs inside the sill - and also the reason why I can't do an interior window).

From my point of view, I want to do as good of a job as possible on the replacement windows for sound attenuation and go from there. I have no concerns about energy efficiency as heat is included in my fees. In any case, my apt tends to overheat from the sun, so I also will have a low e on any option I use.

From my point of view I have to assume the installation will be done professionally as possible with the triple weather stripping so sound doesn't come in through plain air. To me really the only variable under my control is the IGU set up and configuration of the double hung window.

I am going to ask to see if I can have two diff sized panes (e.g., 1/4 and 1/8) b/c my research turned up having that variance helps with attenuation because each pane will block diff frequencies based on thickness.

    Bookmark   November 24, 2013 at 2:54PM
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toddinmn

Maybe consider the Crystal 2600 since it has triple weatherstripping and 1'' glass pack (for greater insulation and sound reduction per their claims).
Even though your not paying heat the tighter window with better glass pack should feel better. I would look at the condensation resistance number as well especially with aluminum in colder weather. Hard to believe they don't have any STC numbers on these windows.

    Bookmark   November 24, 2013 at 3:41PM
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sippelmc

Thanks. I did look at the Crystal 2600 but did not notice they have a 1" IGU. Well, I looked at the wrong part. One spot of the flyer says 7/8 IGU but the spec sheet says 1" so something is amiss. Going to call and check on that Monday. I'm told the 2000 also has triple weather stripping as well, but I think I will call and harass them again and see if I can get an STC out of them as well.

The NYC based companies seem to shy away from any discussion related to attenuation of sound because they don't want to get sued for false promises because, the reality is, its an extremely noisy city and people build up more expectation than replacement windows w/out a secondary interior can deliver (so one rep told me).

This post was edited by sippelmc on Sun, Nov 24, 13 at 15:55

    Bookmark   November 24, 2013 at 3:53PM
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PRO
Windows on Washington

As you stated and found earlier, see if you can get and offset glazing set up.

Let us know how it turns out.

Depending on the depth of the window, you could always go for a window inside of a window. We are getting ready to do that for a client who can change the outside window and is on the 21st floor.

    Bookmark   November 24, 2013 at 4:22PM
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sippelmc

Thanks, I decided to go with the Crystal. I'll make sure they triple weather strip and do whatever sound insulating sealants they need to do. I opted against going with the 1" larger window so that, if the Crystal is not enough, I can still put in an interior window. It doesn't hurt that the Crystal lead time is 4 weeks vs option 2's 12-14 weeks.

    Bookmark   December 1, 2013 at 5:45PM
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etujr

sippelmc, how did your window choice turn out? I live in NYC and am looking at replacing terrible windows. The windows that came with the building are Crystal and I'm sure they are low end. I swear you can hear people whispering on the sidewalk.

    Bookmark   December 25, 2014 at 9:28PM
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