# Home Carpet padding as sound deadner?



## mjgonegm (Jun 21, 2008)

Home Carpet padding as sound deadner?

My negibor just redid her home, will this work?

There is a ton, If you want some and live near the gurnee, IL area Let me know there is plenty to go around.


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## shadowfactory (Oct 20, 2008)

Is it foam? Then no.

Is it MLV? Then yes. 

/End of thread.


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## mjgonegm (Jun 21, 2008)

how can you tell, i will get a pic up.


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## sideout2002 (Jun 1, 2009)

Apparently i can't link as a new member 

Reposting for your info, shoot me a pm if need more info on the foam or can't find it on Amazon.
------------------------------------------
Please don't use home carpet padding. It may work a little but you will get so sick of the smell of that stuff. and it WILL stink!

There are two things you can use. Dynamat type material (dynamat, raamat,second skin, edead) which is actually supposed to be used for vibration control.

Then there is foam (still not home carpet foam), which is Actually For sound deadening. Amazon sells it cheap and it is very easy to use and cut. If you need pics or tips just shoot me a PM. I did my entire car with both dynamat and the edead foam. Rides and sounds like a new car now.


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## mjgonegm (Jun 21, 2008)




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## shadowfactory (Oct 20, 2008)

Using foam as a SOUND BARRIER is useless. It only blocks frequencies whose wavelengths are at least 1/4 of its thickness, so even with 1/2" foam you will only be blocking frequencies waaaaay above 20khz, or outside the range of human hearing.


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## shadowfactory (Oct 20, 2008)

sideout2002 said:


> Then there is foam (still not home carpet foam), which is Actually For sound deadening. Amazon sells it cheap and it is very easy to use and cut. If you need pics or tips just shoot me a PM. I did my entire car with both dynamat and the edead foam. Rides and sounds like a new car now.


While you did achieve something by using the CLD (dynamat) to control panel borne vibrations, the foam did absolutely nothing to block sound from coming into your vehicle. Adding a layer of MLV on top of that foam however, would actually do something to reduce noise, assuming the foam you used actually has a good compression resistance rating. And unless you used neoprene foam, I have a feeling your foam's compression rating sucks.


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## br85 (May 2, 2008)

Some well made polyethylene foams can have with good compression recovery too, depending on how they're manufactured.


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## shadowfactory (Oct 20, 2008)

br85 said:


> Some well made polyethylene foams can have with good compression recovery too, depending on how they're manufactured.



Very true, forgot about those, good point.

p.s. I love your sig. :smug2:


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## cvjoint (Mar 10, 2006)

I'd think it would to some degree. If you want to absorb long frequencies it will probably work better than the foam, which does nothing like people mentioned. I plan on using some old fashion home fiberglass insulation.


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## FoxPro5 (Feb 14, 2006)

shadowfactory said:


> Is it foam? Then no.
> 
> Is it MLV? Then yes.
> 
> /End of thread.


\begin thread....

Mass is mass is mass is mass. Did you know mass is mass and that more mass per unit surface area is THE name of the game for sound refraction/blocking? Yea, it's true. No mo MLV dogma, ok? Thanks. 

Don't bother with carpet padding anything other than padding your carpet. Trust me, I filled a city garbage bin fill of the stuff from my car back in the day cuz I read online that it was a good idea to put in an automobile.


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## FoxPro5 (Feb 14, 2006)

shadowfactory said:


> Using foam as a SOUND BARRIER is useless.


Not useless. If it has good density and mass, as metioned it can be very effective. Good luck finding such foam, though.



> It only blocks frequencies whose wavelengths are at least 1/4 of its thickness, so even with 1/2" foam you will only be blocking frequencies waaaaay above 20khz, or outside the range of human hearing.


On paper, yea. In real world testing you can see fairly respectable NRC figures (even some STC's, too) from like 6# 1/2" composite foam or cotton products.

The 1/4" wavelength thing has to do with absorption. If you study Sabine numbers, you can find absorbers with higher than 1.0 NRC figures do to the this affect at the edges of the material absorbing more than the middle.


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## shadowfactory (Oct 20, 2008)

FoxPro5 said:


> \begin thread....
> 
> Mass is mass is mass is mass. Did you know mass is mass and that more mass per unit surface area is THE name of the game for sound refraction/blocking? Yea, it's true. No mo MLV dogma, ok? Thanks.


I only said MLV because its relatively easy to find, pretty cheap, and somewhat easy to work with. Most people won't bother with making a 'sand glue sandwich' or using lead in their car, and I never said that MLV is the only option out there.


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## shadowfactory (Oct 20, 2008)

FoxPro5 said:


> Not useless. If it has good density and mass, as metioned it can be very effective. Good luck finding such foam, though.


Again, most people won't ever be able to find such dense foam that would make it useful in that application, and as such most foam people actually think of or use actually IS useless. Just because an esoteric version of it exists out there somewhere doesn't mean the average person knows about it, and it definitely isn't what they think of while putting ensolite in their car.


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## Ziggy (Nov 29, 2007)

?/!?


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## dbiegel (Oct 15, 2006)

From the picture you posted, that looks to be an insulation they call "Jute". It seems to be heavily used by car manufacturers as I've seen tons of it in most of the cars I've taken apart. 

I wouldn't bother putting it in a car for a number of reasons:
1) it doesn't seem to be a very good sound insulator (although it might be good thermal if you need that) -- if you're going through all the trouble, you might as well spend a hundred bucks (or more) and get some much better materials as others have suggested.
2) it will absorb moisture, ie at some point start smelling bad, maybe mold or even cause rust if near sheet metal
3) it's probably highly flammable
4) it's thick, so your carpet might not stay right

I imagine the Jute used by car manufacturers is specially treated for issues 2 and 3, doubtful that the home version is.


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## Rudeboy (Oct 16, 2005)

shadowfactory said:


> I only said MLV because its relatively easy to find, pretty cheap, and somewhat easy to work with. Most people won't bother with making a 'sand glue sandwich' or using lead in their car, and I never said that MLV is the only option out there.


At some point you are just looking for low cost substitutes for low cost substitutes. MLV was developed to be a low cost substitute for lead. Most of the alternatives I've seen have enough deficiencies to not be worth the effort. If you can string something together out of material that is free to you, you may come out ahead of the game. Walking the aisles at Home Depot probably won't pay off It's sort of like looking for a cheaper version of cubic zirconia - you're already 99% of the way there.



shadowfactory said:


> Again, most people won't ever be able to find such dense foam that would make it useful in that application, and as such most foam people actually think of or use actually IS useless. Just because an esoteric version of it exists out there somewhere doesn't mean the average person knows about it, and it definitely isn't what they think of while putting ensolite in their car.


Right, rule out the idea that thin foam will be any kind of barrier or do much vibration damping. It's good for two things - attenuating high frequencies and isolating adjacent objects or surfaces. It's possible that the OP's carpet padding might have some use - subject to all of the caveats already listed, but only as a substitute for foam, the least important and least expensive ingredient in the mix.


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## John0540 (Nov 22, 2008)

I used some for my truck roof on top of damplifier, not for sound but for insulation. Along with a sun shade in the front window it works well on hot days.

Plus for a week or so you get that new house smell


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## shadowfactory (Oct 20, 2008)

Rudeboy said:


> Right, rule out the idea that thin foam will be any kind of barrier or do much vibration damping. It's good for two things - attenuating high frequencies and isolating adjacent objects or surfaces. It's possible that the OP's carpet padding might have some use - subject to all of the caveats already listed, but only as a substitute for foam, the least important and least expensive ingredient in the mix.


That's pretty much what I was trying to say, that using thin foam specifically as a noise barrier won't get you anywhere. I never said it doesn't attenuate very high frequencies, or that it doesn't do an admirable job of isolation surfaces from vibrations. In fact, I use to to keep panels from vibrating against one another and it works quite well.


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## DanWiggins (Jun 15, 2005)

Ever worked on an older (pre 1970s) car? The carpets - and behind the back seat, along the firewall, and several other places - were lined with jute carpet pad. It works well, if it's relatively thick. 

It works in doors, too, if you can handle 3/4" thick pad and figure out a good way to support/seal it to the metal.


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## Rudeboy (Oct 16, 2005)

John0540 said:


> I used some for my truck roof on top of damplifier, not for sound but for insulation. Along with a sun shade in the front window it works well on hot days.
> 
> Plus for a week or so you get that new house smell


The roof is one of the few places were I suggest people just use foam or something like this over CLD since most of the noise there is high frequency caused by air turbulence. That application is why I spec'd my foam to natural (light tan) instead of the sexier black that we usually see - may as well get whatever heat reflection you can.


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## FoxPro5 (Feb 14, 2006)

I still have some jute behind the plastic panels in my hatch and it indeed _works_ to some extent. Whether it's worth tearing your interior out just to try to block agressive exhaust, engine and tire noise is totally different. Not a chance in hell it can compete with lead (in the mass/unit surface area category)...and since MLV is it's closest competitor...it's not on MLV's block-ability (STC) either. 

Another way to reduce sound is by diffusing it. And practically anything you put between a noise source and your ears can diffuse sound. If you want to test how well carpet padding works in any regard, duct tape a chunk over your tweeters or midrange and start dropping the xover point until you hear the speaker. At least you'll have some idea at which point the stuff fails to impede the noise source you're after.


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## FoxPro5 (Feb 14, 2006)

Rudeboy said:


> That application is why I spec'd my foam to natural (light tan) instead of the *sexier black *that we usually see - may as well get whatever heat reflection you can.


But, to me, you done still brought sexy back to them sound deaders. Ohhh, and tan? You got my resonant frequency standing straight up, big boy. :surprised::blush:


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## sqshoestring (Jun 19, 2007)

Old cars had that ragwool stuff, it was at least .5" thick and looked like ground t-shirts. Then they would surface one or both sides with a harder tar type layer or tar paper. The stuff worked pretty good though not sure compared to new stuff. Back in the day I used to rip carpet out of Cadillacs and Lincolns and tear that best stuff out for my cars. The old cars would get hot floors also, most of my cars had dual exhausts under there, lol, and it kept them much cooler.

That foam pad is ground foam, recycled if you will. It has various densities. It may help some but likely not as much as other stuff, at that smaller thickness. On the other hand if you really want to know toss it in and see.


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## sideout2002 (Jun 1, 2009)

shadowfactory said:


> While you did achieve something by using the CLD (dynamat) to control panel borne vibrations, the foam did absolutely nothing to block sound from coming into your vehicle. Adding a layer of MLV on top of that foam however, would actually do something to reduce noise, assuming the foam you used actually has a good compression resistance rating. And unless you used neoprene foam, I have a feeling your foam's compression rating sucks.


The edead stuff is closed cell 1/4" dense foam and it absolutely made a huge difference in sound suppression. I drive an STi and there was next to no sound deadening material in it from the factory. Road and exhaust noise are actually acceptable to the wife.


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## 240sxguy (May 28, 2009)

I have quite a bit of this Rubber Carpet Pad that I swiped from my folks after they had carpet installed. Its very heavy. 

Evan


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## FoxPro5 (Feb 14, 2006)

240sxguy said:


> I have quite a bit of this Rubber Carpet Pad that I swiped from my folks after they had carpet installed. Its very heavy.
> 
> Evan


Now you're talking. Should work great as a barrier and would probably not need to be decoupled. Should also conform well if it's soft and flexible.


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## 240sxguy (May 28, 2009)

Stuff is so flexible that I can't even pick it up when its rolled up. The ends flop down and inevitably throw me off balance. Been packing that stuff around for a year now!

Evan


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## mitchyz250f (May 14, 2005)

FoxPro; When I looked at the images there seems to be thick and thin sections of the pad. Would the sound go through the thinner sections instead of being blocked? 

Also, what is the weight per yard or foot?


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## FoxPro5 (Feb 14, 2006)

mitchyz250f said:


> Would the sound go through the thinner sections instead of being blocked?


Yes, to a degree. Blocking is never 100% and lower octave sound goes right through concrete, so it depends on the mass and the frequency. At 1 lb/sqft, for ex, this padding is probably good for 12-14 dB of attenuation at 250 hz. That's a predicted value based on Mass Law (true for anything weighing 1 lb/sqft), not a measured one. Real world is always different. 

*edit* Oh, I get what you're asking now after reading it again. Will the sound make it through the thin parts since the padding is not solid and uniform throughout? Good question, I don't know.  I'd guess no if there was no actual gap for air to pass though. Since it's a dirt barrier, then I'd think it would be a pretty solid noise barrier too. But who knows?



> Also, what is the weight per yard or foot?


Don't know. I've never used it, just have seen it in houses. It's pretty heavy stuff and I'd think the convoluted surface helps it absorb a little too.


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## mjgonegm (Jun 21, 2008)

Just then hijacked my thread


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