Testing my wall's STC Rating - AVS | Home Theater Discussions And Reviews
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post #1 of 10 Old 05-09-2012, 12:46 PM - Thread Starter
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Anyone have any insight into how to get a professional STC rating done? My newly developed condo was developed without sound insulation, and we can't really make any progress with the city and developer until we "prove" that it doesn't meet code.

I've called a bunch of building inspection companies, but they all claim this is one area they don't test. There's got to be some organization that tests STC ratings...

Any help is much appreciated!
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post #2 of 10 Old 05-09-2012, 02:09 PM
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If you know how its constructed, you can use a chart like this one
http://www.sae.edu/reference_materia...TC%20Chart.htm
But this is only if its constructed properly....caulked around perimeters etc.

I am a wall and ceiling contractor.....a few jobs I've done, radio stations, police stations etc have had wall assemblies tested to see if they meet standards. They use a small machine that looks like a jet engine then test the other side with a meter.
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post #3 of 10 Old 05-10-2012, 04:43 PM
 
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If you really need "it" tested, you can contact these folks.

But a few issues that you will need to clarify first...

You mention STC measure specifically. This is a vague measure that is not necessarily a very useful practical measure as it fails to address some of the most problematic sources of practical sound transmission (specifically low frequency energy). One can meet STC levels and still be mired in what is an otherwise untenable subjective circumstance - so it pays to precisely define the nature of your perceived objection and then to identify and pursue a solution in a manner referencing legally defined standards that will more precisely address the specific problematic aspects to which you object.

Note also, that STC ratings are not generally used for the net large composite structures, but rather for the various constituent building 'components'. A fact that will be difficult to address if, say a wall meets the STC designation, but the flanking vector renders it nearly worthless. Yet another reason to holistically evaluate and to define the nature of the problem and to THEN devise a plan that satisfies the legal requirements as well as the acoustical standard of behavior... Assuming of course that you are not simply pursuing a Pyrrhic victory...

In other words, more precisely defining the problem determines what acoustical measure paired with what codified standard it is most appropriate to pursue. It makes little sense to pursue standard STC rating levels if, for instance, the preponderance of the problem is sub 100 Hz energy - behavior that is effectively outside the effective range of the STC measure...or if. for instance, the city codes do not reference STC standards... That would be a case were the wrong standard and tool has been chosen to reference a specific behavioral case, and you would hopefully want to chose a more appropriate standard that more adequately addresses the real nature of the problem as well as the legally enforceable standards.

You would do well to better define your criteria and pick the right tool for the job...

Additionally, related to this, since you reference the city, you had best find out precisely what the local codes and the specific noise criteria they reference. As if you will be n for a surprise if you reference other measures, while they may make for an utterly fascinating presentation, may very well be relegated to very enlightening, and moot point if they do not have legal standing as a result of codes failing to designate their objective legal applicability.

Specific site related noise is not difficult to evaluate, but the measure used for standards evaluation as well as the procedures to be used are defined and any investigation must be compliant with said best practices, as well as calibration, etc. Oft times NLA (noise level analysis) over time is a useful measure - again, dependent upon precedent and code. And it is your due diligence to discover these and to put together an effective and legally admissible strategy.

So, once the specific appropriate terminology relating to the specific defined quantifiable measures are identified, the rest is a pretty routine process. Unfortunately, 2/3 of the battle is determining the common language that all parties can reference in the discussion, thus allowing an objective determination of both the real objectively defined problem as well as enabling the establishment of an objectively verifiable solution - and hopefully one that is ultimately useful to your goals.
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post #4 of 10 Old 01-22-2015, 07:10 PM
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STC Rating- New Windows

I have a similar situation i am trying to figure out. I live in a condo on a busy street and traffic noise is my primary issue. the wall facing the street has 4 aluminum dual pane windows that look like original construction (i.e., 35 years old). the wall construction looks like dual drywall, wood studs, and my guess is R-11 batt insulation. the exterior of the structure is wood paneling.

I want to determine if new vinyl (STC 32) windows will provide adequate noise reduction or if i need to get either window inserts or acoustical windows.

My approach is to determine the existing wall configurations STC rating and then the future configuration (i.e., with vinyl STC 32 rated windows).

I conducted noise measurements outside my wall and inside the wall. The measurements were as follows

Outside: 66.7 dBA Lmax, 56.7 Leq (15 minute measurement)
Inside: 56.5 Lmax, 47.6 Leq (15 minutes measurement)

Does this mean my wall configuration is an STC of about 10?? I am not sure which metric i should be using for STC, average or max? My meter was set at A-weighted with and slow detector.

If that is the case, assuming my wall is STC 38 as i have seen on many charts online, then my windows are in fact the weak point and new windows with higher STC rating should reduce noise.


How can i calculate the STC (or sound reduction) of my wall configuration with the new windows?
Any ideas of how to calculate the STC of my existing windows?
Thanks
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post #5 of 10 Old 01-22-2015, 07:49 PM
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Quote:
Originally Posted by Dimitri Antoniou View Post
I have a similar situation i am trying to figure out. I live in a condo on a busy street and traffic noise is my primary issue. the wall facing the street has 4 aluminum dual pane windows that look like original construction (i.e., 35 years old). the wall construction looks like dual drywall, wood studs, and my guess is R-11 batt insulation. the exterior of the structure is wood paneling.

I want to determine if new vinyl (STC 32) windows will provide adequate noise reduction or if i need to get either window inserts or acoustical windows.

My approach is to determine the existing wall configurations STC rating and then the future configuration (i.e., with vinyl STC 32 rated windows).

I conducted noise measurements outside my wall and inside the wall. The measurements were as follows

Outside: 66.7 dBA Lmax, 56.7 Leq (15 minute measurement)
Inside: 56.5 Lmax, 47.6 Leq (15 minutes measurement)

Does this mean my wall configuration is an STC of about 10?? I am not sure which metric i should be using for STC, average or max? My meter was set at A-weighted with and slow detector.

If that is the case, assuming my wall is STC 38 as i have seen on many charts online, then my windows are in fact the weak point and new windows with higher STC rating should reduce noise.


How can i calculate the STC (or sound reduction) of my wall configuration with the new windows?
Any ideas of how to calculate the STC of my existing windows?
Thanks
The noise reduction with windows isn't about the frame material, it's about the number of panes. To get a significant reduction you'd have to go from two to three. My windows are all triple pane and they're pretty quiet, but by no means do they eliminate traffic noise.

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post #6 of 10 Old 01-23-2015, 09:12 AM - Thread Starter
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Three panes of glass may be overkill. Two panes of dissimilar glass would probably provide just as much noise reduction.

http://www.jeld-wen.com/catalog/wind...rmance-windows

I'm not sure where you live, and by no means am I even close to an expert, but aluminum is metal and therefore it can expand and contract with weather. If they are ~35 years old, they may no longer be properly fit to the wall opening they were meant for. A properly installed window is the biggest key to outdoor noise reduction.

My advice - again, not expert advice at all - is to go for new vinyl windows with dual pane, dissimilar glass and make sure they're installed properly. You'll save a lot of money over three pane glass, and it may be just as adequate. If that doesn't work as much as you'd like, you could always then add an insert. It would either be the same cost as three pane windows, or potentially cheaper.

http://www.supersoundproofingsales.c...s/products/26/

Just my two cents.
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post #7 of 10 Old 01-23-2015, 12:51 PM
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Originally Posted by theshiv View Post
Three panes of glass may be overkill. Two panes of dissimilar glass would probably provide just as much noise reduction.
http://www.jeld-wen.com/catalog/wind...rmance-windows
There's some truth to what's in that link, but not much. A window that really gave significant transmission reduction results would have a vacuum between the panes, but that would be prohibitively expensive. Using different thickness panes wouldn't actually reduce transmission per se. It would result in the two panes having different resonant frequencies, which means that the tendency of the window to act as a resonant source on it's own would be reduced, but that's a different matter than transmission reduction.
OTOH aluminum is undoubtedly the worst material ever devised for window frames, as it is an efficient conductor of heat. It's worthwhile to get rid of aluminum for that reason alone.

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post #8 of 10 Old 01-23-2015, 11:40 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post
There's some truth to what's in that link, but not much. A window that really gave significant transmission reduction results would have a vacuum between the panes, but that would be prohibitively expensive. Using different thickness panes wouldn't actually reduce transmission per se. It would result in the two panes having different resonant frequencies, which means that the tendency of the window to act as a resonant source on it's own would be reduced, but that's a different matter than transmission reduction.
OTOH aluminum is undoubtedly the worst material ever devised for window frames, as it is an efficient conductor of heat. It's worthwhile to get rid of aluminum for that reason alone.
Wouldnt then adding inserts to my current configuration be the cheapest/quickest and result in the noise reduction benefit (3rd pane and additional airspace) as well as energy savings?

Can anyone speak to the STC calculations?

I dont want to just spend aprox $7,000 for new windows then another few thousand for inserts if that doesnt work.

thanks
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post #9 of 10 Old Yesterday, 07:34 AM
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Quote:
Originally Posted by Dimitri Antoniou View Post
Wouldnt then adding inserts to my current configuration be the cheapest/quickest and result in the noise reduction benefit (3rd pane and additional airspace) as well as energy savings?
That's what I did, adding a layer of 1/10" plastic glazing to my double pane windows. They're vinyl clad wooden frame, which I installed, replacing the original 1938 vintage double hung single panes. You can use double sided foam adhesive tape, which will have the added benefit of isolating the aluminum from your heated/cooled living space.

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post #10 of 10 Old Today, 06:33 AM - Thread Starter
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It would definitely be the cheapest and quickest, but it may not provide total reduction. Your 35 year old aluminum windows may no longer be seated properly due to expansion/shrinkage. Definitely start with adding a 3rd pane, but if that doesn't work you need to think about replacing the windows to ensure that there's a proper seal between the house frame and the window itself.
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