Author Topic: Soundproofing failure  (Read 10922 times)

author6659

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Soundproofing failure
« on: January 15, 2008, 02:37:20 AM »
Just wanted to post our experience...

We wanted to block traffic noise from an upstairs room we're using as a home office. The road is about 100 yards away, a 30 mph road with lots of tractor trailers and motorcycles. To the existing wall, we added a second layer of 5/8 inch drywall, with green glue sandwiched between. To the glass slider, we added one of the expensive custom windows from soundproofwindows.com.

The whole thing cost us over a thousand dollars, and after waiting a month to let the green glue "cure", I regret to say that we hear virtually no difference. The low rumble of the trucks and motorcycles is as loud and distinctive and disturbing as ever. Very disappointing.

johnbergstromslc

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Re: Soundproofing failure
« Reply #1 on: January 15, 2008, 06:24:47 PM »
Did you only do the exterior walls?  Don't forget about the ceiling. Low frequency sound radiates from all directions.

Mark Daveis

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Re: Soundproofing failure
« Reply #2 on: January 15, 2008, 09:33:22 PM »
John is right you need to look at all the walls and floor and roof. Any weak points where there is low mass will make your efforts worthless. Green glue will help stop some of the vibration/conduction but doubling the mass of the wall will only give you 3 or 4 stc points at most. To put it bluntly I have spent almost 9000 to soundproof one room and it is still not yet finished so more expense is likely.
The only way to reduce low frequency sounds is to use huge amounts of mass which may not be practical or use a air gap which means build a room within a room with a floating floor and its own roof but this works better and uses less mass. :)

author6659

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Re: Soundproofing failure
« Reply #3 on: January 17, 2008, 02:26:48 PM »
Thanks, John and Mark, your responses were very helpful and much appreciated.

I hope other people will learn from our experience that trying to stop road noise is much more complex than the companies selling windows and green glue might lead you to believe. We were misled by marketing materials and STC ratings into believing that the window would solve most of our problems and that doing the walls would take care of the rest. Obviously that isn't the case and we learned our lesson.

johnbergstromslc

  • Guest
Re: Soundproofing failure
« Reply #4 on: January 18, 2008, 03:53:03 PM »
Well, you really have to soundproof at the entire room and not neglect any surface. 

It's also possible that the noise reduction is there, but doesn't subjectively live up to your expectations. 

It's a good idea to invest 50 bucks in a cheap sound-level meter so you can get an accurate measurement of whether or not your efforts are paying off.

A 3 dB reduction isn't usually perceptible, a 5 dB reduction is somewhat noticeable and a 10 dB is pretty good reduction.  But if you were expecting all the noise to go away from minimal effort, well, that's just not realistic. 

Sometimes, aftermarket surface-treatments aren't enough.  Sometimes, you gotta tear the room apart and do it right - sealing, insulation, decoupling, increased mass.  As I've said, the damping products (Green Glue, Quietrock, etc.) should be the icing on the cake, not the main strategy.   

joel

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Re: Soundproofing failure
« Reply #5 on: September 26, 2008, 04:54:55 PM »
I couldn't agree with John and Mark more.  Great posts, both of you.

jaskit

  • Guest
Re: Soundproofing failure
« Reply #6 on: May 08, 2009, 05:01:15 PM »
John is right you need to look at all the walls and floor and roof. Any weak points where there is low mass will make your efforts worthless. Green glue will help stop some of the vibration/conduction but doubling the mass of the wall will only give you 3 or 4 stc points at most. To put it bluntly I have spent almost 9000 to soundproof one room and it is still not yet finished so more expense is likely.
The only way to reduce low frequency sounds is to use huge amounts of mass which may not be practical or use a air gap which means build a room within a room with a floating floor and its own roof but this works better and uses less mass.

johnbergstromslc

  • Guest
Re: Soundproofing failure
« Reply #7 on: May 08, 2009, 06:30:19 PM »
John is right you need to look at all the walls and floor and roof. Any weak points where there is low mass will make your efforts worthless. Green glue will help stop some of the vibration/conduction but doubling the mass of the wall will only give you 3 or 4 stc points at most. To put it bluntly I have spent almost 9000 to soundproof one room and it is still not yet finished so more expense is likely.
The only way to reduce low frequency sounds is to use huge amounts of mass which may not be practical or use a air gap which means build a room within a room with a floating floor and its own roof but this works better and uses less mass.

Do you have any thoughts of your own, or do you just rip off other people's posts?

If you don't want to make an effort or contribution to the forum, please leave.

jel111

  • Guest
Re: Soundproofing failure
« Reply #8 on: January 09, 2010, 06:43:54 PM »
    I am in a building that has brick outside walls so that is not an issue but the ceiling and the floors have no insulation are just wood joists. Now the guy upstairs installed the secondary windows on the inside of his cheap double hung and the reduction of noise was awesome. I think that they charge entirely to much for these windows. I got a quote for 590 bucks for one window. These windows are much cheaper to make than a regular double hung. That is crazy. The install is easy and if you are at all inclined I think anyone could do it. The objective is to get a good seal and to be level and square. I am going to try the the magnet one because that is very cheap. Magntite charges 1.50 a foot for this tape but you can get it online for much cheaper. The angle brackets are cheap as well. So I will try that and let you know. The more I read on this stuff the more I see these guys taking advantage of people in distress. There is a foam that you can shoot into your ceiling that has great insulation value and sound qualities. Not the cellulose cuz that settles and over time does not work. I don't see this green glue possibly doing anything more than regular old liquid nails which is much cheaper. It gives you the adhesive and the gap that would help. As we all know though that does not do much. You need a sound absorbing material. Regular drywall won't work. They sell a sound board that works better. So I know this is long but I would investigate first before spending all that money on windows. The gap between is the most important thing. The only windows I have seen that work have that gap.

Randy S

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Re: Soundproofing failure
« Reply #9 on: March 02, 2010, 06:58:42 PM »
The only thing I can agree with in your post is about the windows, all your other statements are not correct.

Expansion foams will allow more pathways for impact and low frequency to easily pass, not only that but you also still have all the hard connections of the substraite/ceiling.

Green Glue IS like the icing on the cake and it definitely reduces reverb time in the wall, also because its a visco elastic material it turns the vibration into heat. Liquid nail will harden and help transmit vibration, also you could create a resonence chamber between the 2 layers of drywall by creating that small of a gap.

Standard 5/8" drywall has a higher STC rating than sound board every day of the week.. it is for absorption not barrier.

Randy Sieg

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