Homasote 440 SoundBarrier board, DD+GG alternative? - AVS Forum
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post #1 of 8 Old 02-06-2010, 07:41 AM - Thread Starter
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Friend told me his cousin's place carry a sound dampening product called 440 Soundbarrier manufactured by Homesote, here is the manufacture's product link: http://www.homasote.com/products/440-Soundbarrier.aspx

It claims the 1/2" board to be able to achieve STC 51 rating for simple wall assembly and 54 for floor and ceiling assembly. Wonder if anyone has real experiences with this product and how is to compare to DD+GG which claims to be able achieve 55 STC, but depends on types of wall assembly, 440 board can go as high as 66 STC with decoupled double wall and 440 board on on both side: http://www.homasote.com/Catalogs/200...Assemblies.pdf.

If it is as it claimed, could it be the DD+GG alternative? From the surface, it seems much easier to install and is probably more cost effective.
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post #2 of 8 Old 02-06-2010, 08:03 AM
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STC doesn't take into account low frequency which is what we are trying to mostly block using DD/GG.

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post #3 of 8 Old 02-06-2010, 08:34 AM
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These sound board products are marketed under many different names. In general they are made from waste material from the lumber industry.

They are light weight and a bit spongy, so the hope of some sound isolation benefit springs forth.

Let's look at the physics of what is available to us in out little soundproofing toolbox. There are 4 and only 4 elements of soundproofing:

#1 we have Decoupling. Having these sound boards on our studs doesn't reduce the surface area of contact, not does it establish the required decoupled mass-air(spring)-mass system we're looking for. So these sound boards do not decouple.

#2 we have Absorption. For absorption within a defined air cavity we want a medium density absorptive material. Sound boards are far too dense for the type of absorption we need so in effect, sound boards do not offer absorption.

#3 we have Mass. The low density of the sound boards certainly don't replace drywall as they are at best 1/2 the weight of proper 5/5" drywall. Sound boards do not offer significant mass.

#4 we have Damping. While the soundboards may be somewhat damped themselves, they do not significantly damp the drywall they are in contact with. Sound boards do not effectively damp what they are in contact with.

So the sound boards find themselves in an undefined category. They arguably do a little but not to the point where we would take up valuable resources to incorporate them.

Some other interesting facts:

The assembly requires that you install the drywall with screws that are anchored into the sound board, NOT the studs. The thought of my drywall being held in place by screwing to this somewhat dense cardboard isn't comforting. The product test scores plummet when the surface drywall is properly attached to the studs.

Even with the questionable attachment recommendation, the overall STC scores (STC 51 on steel studs) are several points below what you would see if you used the same thickness of damped drywall (STC 61 on steel)

Lastly and most importantly, the low frequencies that are not measured by STC (STC stops at 125 Hz) are much superior in a more massive and highly damped system. If OITC calculations were available (measuring down to 80Hz), the differences in the systems would be even more dramatic.

The products from these manufacturers are well known in the acoustics industry to not be forthcoming with the raw data associated with their Transmission Loss Tests (ASTM e-90). Generally is the raw data is retained, there's a reason.

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post #4 of 8 Old 02-06-2010, 09:39 AM - Thread Starter
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Thanks Ted, I am glad that you weighed in, opinions from experts like yourself are always very valuable to us.

But just let me play devil's advocacy here. Let's say that the manufacture's installation method is worrisome by attaching drywall to the sound board rather that to the studs, but, based on your 4 points of soundproofing, 1, decoupling, can apply the same staggered or double wall with sound board, 2, absorption, sound board may be denser, but it still less denser than dry wall, and it is sponge, so it should be able to absorb sound in some degree, how much, I have no idea, 3, mass, you are right, sound board is light, it does not provide the mass by itself alone, but again, if it is sandwiched between two drywalls, then it may achieve similar mass as DD+GG and 4, damping, again, DD+sound board may provide good damping.

Hey, speaking of, here is a wild idea, my bed and pillow are both made of memory foam, that stuff is probably a good sound absorption material, 1" foam put in the wall panel instead of OC703 linacoustic?
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post #5 of 8 Old 02-06-2010, 10:07 AM
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Quote:
Originally Posted by theWalkinator View Post

Let's say that the manufacture's installation method is worrisome by attaching drywall to the sound board rather that to the studs,

This is worrisome, wouldn't we all agree?

but, based on your 4 points of soundproofing,

1, decoupling, can apply the same staggered or double wall with sound board,

Yes, but the point was that the sound boards are doing little for decoupling in a single wall and certainly nothing in a system that is already decoupled using proper techniques.

2, absorption, sound board may be denser, but it still less denser than dry wall, and it is sponge, so it should be able to absorb sound in some degree, how much, I have no idea,

I have an idea... none arguably of any practical value at all for the problematic low frequencies we agonize over.

3, mass, you are right, sound board is light, it does not provide the mass by itself alone, but again, if it is sandwiched between two drywalls, then it may achieve similar mass as DD+GG

Actually DD and SB would be more mass than DD + GG but you would sacrifice damping in this situation. A very bad trade. So even if the double drywall + sound board weighed more, it would be poorly damped in comparison.

4, damping, again, DD+sound board may provide good damping.

But it simply does not. That's my point. The soundboard can't effectively damp the bending waves travelling through the panels, nor increase the internal friction of the system and damp the way an actual damping material does.

Hey, speaking of, here is a wild idea, my bed and pillow are both made of memory foam, that stuff is probably a good sound absorption material, 1" foam put in the wall panel instead of OC703 linacoustic?

No it's not a good material to use just about anywhere in out builds, I'm afraid.

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post #6 of 8 Old 02-07-2010, 04:07 AM
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Quote:
Originally Posted by ted white View Post

these sound board products are marketed under many different names.
...
The products from these manufacturers are well known in the acoustics industry to not be forthcoming with the raw data associated with their transmission loss tests (astm e-90). Generally is the raw data is retained, there's a reason.

+1

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post #7 of 8 Old 03-01-2010, 07:45 AM
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Quote:
Originally Posted by Terry Montlick View Post

+1

I s/w tech support at the manufacturer of homasote. Basically, their business model is high volume commercial apps, like hotels, multifamily, highrise office. I asked him why their product isn't trumpeted by the forums and he said, they don't want low volume high margin business such as high end theater or DIY markets, so they don't pursue that. He was adamant that their product offers the stated ratings for noise suppression however.
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post #8 of 8 Old 03-01-2010, 07:51 AM
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In the acoustics business test reports are required. Could be a 20 story hotel or a single listening room. Test data is required. If there's no test data, there's no spec into a (large or small) job.

These sound boards were tested with the finish drywall being secured to the sound board rather than the stud. Screwing to the studs = conduction = worse test performance. However, screwing your drywall to a material that is similar to a thick cardboard doesn't give me comfort.

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