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Author Topic: Does glass thickness matter?  (Read 13592 times)

lunyc

  • Guest
Does glass thickness matter?
« on: September 14, 2006, 12:05:38 AM »

Hi, I'm getting estimates for soundproof windows this week, and am getting conflicting info on the importance of glass thickness. One company is trying to sell me 1/2" laminated windows (the most expensive they offer), saying the thickest glass will block out the most noise, and that I will get about 80% noise reduction.

But another company says that all I need is 1/4" laminated windows (less expensive) because the space between my existing window and the soundproof window will also help block out the noise and that I will achieve 90% noise reduction.

There is a $400 per window difference between the two estimates, so I want to make sure I make the best decision. Can anyone please explain which estimate is accurate? Thanks!

johnbergstromslc

  • Guest
Re: Does glass thickness matter?
« Reply #1 on: September 14, 2006, 10:21:13 PM »

If the argument was for the installation of both window panes (1/4" vs. 1/2") then 1/2" would be clearly superior.  But since a variable is the double glazed (I assume) window already installed, that changes the equation.

Assuming you have a 4" airspace between windows, upgrading to 1/2" thick glass will get you an additional 2-3 dB of attenuation, barely even noticeable and probably not worth the extra cost.  

So go with the 1/4" and spend the $400 on something else.  Just make sure both windows are caulked up well to ensure good performance.

lunyc

  • Guest
Re: Does glass thickness matter?
« Reply #2 on: September 14, 2006, 11:36:30 PM »

Thanks, John. My current windows are double-paned. Does it matter that the noise I am trying to block are trains that go by outside my apartment? I'm on the 6th floor and the trains are on ground level.

I got the company which says the 1/4" laminated glass will work just as well as 1/2" laminated to give me an explanation in writing. Below is what they say. Please let me know what you think, thanks!

"The scientific basis behind noise control using secondary windows starts with a properly integrated frame and glass assembly of a design that expressly attenuates the sound waves. The actual decrease obtained is proportional to the dead air space, between the original and secondary windows. Because of the acoustical properties required in a soundproofing interior window, overly thick glass is actually less effective than the properly sized glass that we use in our patented windows to obtain the best results."


Thanks again!

johnbergstromslc

  • Guest
Re: Does glass thickness matter?
« Reply #3 on: September 17, 2006, 12:00:43 AM »

Well, if it's train noise you're trying to block, you might want to consider spending the extra $400.  Transportation noise is heavily weighted in the lower frequencies, and the more mass the better...

As I've said, 1/2" will get you an additional 2-3 dB of attenuation, but maybe more in the lower frequencies.  It could make a big difference.

As for the companies claims, I have no problem with their first sentence, and I'll let the second one slide, even though it is really a half-truth - mass is important, but in rare circumstances resonances can make the thicker glass less effective.  As for the third sentence, well, that's just marketing....

It might be a good investment to have an acoustical consultant come out and measure the noise you're trying to block.  He/she might charge you $100 and you'll be able to make a better decision that way.

What kind of airspace are you looking at?  If you give me a day or two, I can consult my reference material and give you detailed data on transmission loss values and STC ratings.


lunyc

  • Guest
Re: Does glass thickness matter?
« Reply #4 on: October 03, 2006, 01:12:59 AM »

Hi John,

Sorry, I never got notified that you replied.

Yes, I would like to meet with an acoustical consultant. I'll look into it. Can you recommend one in NYC?

All the companies who've given me estimates say that there would be a 3 to 4" airspace between my existing window and the soundproof window.


Thanks again!
lunyc

johnbergstromslc

  • Guest
Re: Does glass thickness matter?
« Reply #5 on: October 04, 2006, 12:38:49 AM »

Sorry, don't know any consultants in NYC - I live out west.

A 3-4" airspace is perfect - not too small, not too big.