Author Topic: Are STC's "cumulative"? window soundproofing  (Read 3296 times)

Jack Lin

  • Guest
Are STC's "cumulative"? window soundproofing
« on: January 07, 2002, 06:26:33 AM »
My apartment's bedroom window leaks sound like nothing else... it's so bad I can understand sidewalk conversations (I'm on the 2nd floor facing the street). I know they are double pane vinyl frames but it's probably very low quality & STC rating. I was thinking of installing a clear vinyl (1 lb/ft) curtain in the window sill, and/or a window plug using the Super Soundproofing Mat.
 I have a few questions:
- Based on my research (and the fact I can understand spoken conversations) I'm guessing my windows currently have an STC of around 25, according to Hufcor's site. The 1 lb/ft clear vinyl has an STC rating of 26. If properly installed and sealed, would I thus be able to get an overal STC of around 51?
- What is the STC of the window plug? For the sake of more light I would prefer a clear vinyl curtain... however, if the window plug is significantly better I would be swayed.
- Would applying any sort of clear vinyl liner or laminate to the current plastic window panes improve the STC at all? e.g. sticking the thinner clear vinyl to the windows, plus hanging the thick clear vinyl a couple inches away...
- My windowsill is about 5 inches deep, but since my bed is directly up against it, I'd prefer to install any plug or curtain as close to the window as possible. Does more air separation b/t the window and the sound barrier improve the effect significantly? E.g. 1 inch away from the window vs. 4 inches away.
 FYI, the 3 main sources of sound I want to remove are: spoken conversations, car alarms, and garbage trucks.
 This is a fantastic site. Thank you for all your help!!
 Jack

Adrian Lafleur

  • Guest
Re: Are STC's "cumulative"? window soundproofing
« Reply #1 on: February 14, 2002, 04:27:26 AM »
No STC's are not accumalitive.  It sounds like your prime window is a very basic window.  If you add a curtain with STC 26 on top of your window of STC 25 you might expect the performance to increast to STC 30-34.  There is a diminishing return.
The larger the air cavity the better the noise reduciton.  Aim for 4 inches (100mm) You want to make the window unit as air tight as possible to stop noise leaking in and you want to minimize the vibration coming through (i.e heavier the better and larger air cavity is better).  
Hope this helps.

The conversation noise will be easy to kill but the garbage trucks pose a bigger problem.
Regards,
Adrian
Magnetite - Inside Insulating Window System
www.magnetite.com.au


Christopher Smith

  • Guest
Re: Are STC's "cumulative"? window soundproofing
« Reply #2 on: February 28, 2002, 09:55:53 PM »
No.  STC is logarithmic, so an STC of 26 provides twice as much noise reduction of an STC of 25.
: My apartment's bedroom window leaks sound like nothing else... it's so bad I can understand sidewalk conversations (I'm on the 2nd floor facing the street). I know they are double pane vinyl frames but it's probably very low quality & STC rating. I was thinking of installing a clear vinyl (1 lb/ft) curtain in the window sill, and/or a window plug using the Super Soundproofing Mat.
:   I have a few questions:
: - Based on my research (and the fact I can understand spoken conversations) I'm guessing my windows currently have an STC of around 25, according to Hufcor's site. The 1 lb/ft clear vinyl has an STC rating of 26. If properly installed and sealed, would I thus be able to get an overal STC of around 51?
: - What is the STC of the window plug? For the sake of more light I would prefer a clear vinyl curtain... however, if the window plug is significantly better I would be swayed.
: - Would applying any sort of clear vinyl liner or laminate to the current plastic window panes improve the STC at all? e.g. sticking the thinner clear vinyl to the windows, plus hanging the thick clear vinyl a couple inches away...
: - My windowsill is about 5 inches deep, but since my bed is directly up against it, I'd prefer to install any plug or curtain as close to the window as possible. Does more air separation b/t the window and the sound barrier improve the effect significantly? E.g. 1 inch away from the window vs. 4 inches away.
:   FYI, the 3 main sources of sound I want to remove are: spoken conversations, car alarms, and garbage trucks.
:   This is a fantastic site. Thank you for all your help!!
:   Jack


 

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