predgw

Egg cartons

Okay, this may sound crazy but I am wondering if it would help. My budget will not allow the expensive accoustic ceiling tiles. I was planning on 5/8" drwall on the ceiling.( HT room in the basement) I want to beef up the sound insulation from the basement to the room above. If I glue empty(of course) egg cartons to the subfloor in between the floor joist will that help? These would be opened up so the inside of the cover and inside of the egg holders are facing the subfloor. This would essential be free sound proofing. I would then go ahead and install the 5/8" drywall and the egg cartons would never be seen. What do you think? Thanks

BruceSpielbauer

Re: Egg cartons

You have fallen victim to a very longstanding and widespread myth, that the use of egg cartons can somehow result in sound isolation (what most people call soundproofing). This has been tested and re-tested, and every lab that has given it a go has reported that egg cartons actually do not do much of anything at all to help if your goal is to reduce the amount of sound which travels out of an area, or to reduce the amount of sound which travels into an area. It is useless as a sound isolation technique.

"One common misconception in soundproofing is that filling the wall with egg cartons will reduce noise transmissions between rooms. In actuality, test results have shown that filling your wall with egg cartons will not produce any measurable reduction in sound transmission between rooms."

-Source, Soundproofoam.com;

Worse, egg cartons are a huge fire hazard. HUGE. Take one outside, find a safe area nowhere near anything -- really! -- and hold a flame close to an egg carton. Watch how quickly it ignites, and how quickly it is reduced to ash.

It does have some useful purpose in sound TREATMENT, if properly applied. It can bring a room closer to being what is often called a "dead room," useful in many recording situations. Thus, a lot of teens who dreamed of building their own recording studio in dad's basement back in the 70s collected them, and then tried to attach them to the walls. However, the potential for disaster due to the fire hazard discussed above makes it unwise even in a specialized situation such as this. There are other alternatives.

If the goal is sound isolation -- reducing the audio that escapes from the room, then never consider egg cartons.

Instead, use only techniques that have been tested in labs and shown to have effective results. Some of these include using double stud walls in construction, for example, or using complete double walls; or, simply doubling up on the drywall, applying a second layer on top of the first layer all around. THOSE techniques will all reduce sound transmission, and some will yield greater results than others.

IF you have the luxury of spending big bucks, then you can also try commercially available products (such as Green Glue, Quiet Rock, etc.,) but you should take exactly the same approach. You should invest your money only in those products that have been tested in labs and shown to have effective results.

-Bruce
-The ultimate add-on for your Home Theater: http://www.S2Digital.com

BruceSpielbauer

Re: Egg cartons

A couple of further thoughts, and clarifications...

Your plan to use 5/8" drywall rather than "expensive ceiling tiles" is a step in the right direction. Those acoustic ceiling tiles will NEVER be as effective as sheets of drywall, if the goal is to prevent sound from traveling. This is due to the mass of drywall. And, yes, this has been demonstrated repeatedly in lab tests, even using those ceiling tiles which are a bit heavier and are therefore advertised as "soundproofing ceiling tiles." Those expensive ones may be better than regular ceiling tiles, but they rank far below drywall.

And, your choice of 5/8" instead of 1/2 inch is another improvement. The extra mass helps.

You can further improve this by adding a second layer of 5/8" to the first. Why? Even more mass.

I did two layers of 5/8" all around. When it came to the ceiling, I also made efforts to try to "partially decouple" the drywall from the basement rafters overhead. I bought hardware for this (RSIC clips is the type I used, and there is a seond product that also can do this). I attached the RSIC clips directly to the rafters overhead (they screw on). Then, I attached long strips of hat channel to those RSIC clips. Then, I screwed a layer of heavy 5/8" drywall to the hat channel. Then, I glued and screwed a second layer of heavy 5/8" drywall to the first layer.

I also used some hardware to try to partially decouple the stud walls from the rest of the house, including the rafters above. Then, I hit all walls with two layers of the 5/8."

I went further, though... I used a product called Green Glue between the two layers of drywall.

I went even further... I actually built two separate stud walls, right next to one another. I left a one inch air gap between the two stud walls.

Overkill? Sure. But, I wanted things quiet, and I did not want my sound to travel. This also meant two separate doors, and both had to be exterior doors, solid core, for the extra mass. And, I sealed things up tight, even the tiny holes in electric boxes. Caulked all seams. Tried to seal all air gaps. I even used lined ductwork for both the supplies and the returns, to try to stop the sound from escaping through ductwork to the rest of the house.


Did this work? Incredibly well, except in one way.

The sound MOSTLY stops right there. I can crank it up VERY loud, and you cannot even tell if you are standing right outside the room in my basement. People open those two heavy doors, though, and they are blown away.

The same is true, upstairs.

EXCEPT for the subwoofer noise. That LFE noise we all tend to like so much is also the most difficult to try to suppress from traveling. This is why you can hear that kid with the large subwoofer in his car more than a block away, but you only hear the the "THOOOMPH! THOOOMPH THOOMPH! from that huge distance. When he gets close enough, you might hear the rest of the music, and the vocals. The low frequency stuff TRAVELS, and it is by far the toughest to try to stop. By far. The midrange and the high frequencies are easier to suppress.

So, the subwoofer thump can still be heard (faintly) and even felt (faintly) on my first floor above. When I really crank it up. It is faint. But, it is there. I reduced it a lot, I know. My subwoofer is excellent (a medium-sized SVS) and it is powered by an amp which is overkill for the room. This subwoofer cannot be heard or felt on the second floor above that, though.... where the bedrooms are. We own a two story home with a typical full basement.

The rest of the audio cannot be heard at all on the first floor.

(Just thought you should know what to expect, even if you decide to go all out).

Consider: staggered-stud walls (they cost almost nothing more than a regular stud wall). This does not mean two walls, like I built. it just means that the inner dryall is attached to completely different studs than the outer drywall, which reduced transfer through vibration. A big help, for not much more money. Also, consider if adding the second layer of drywall would add a lot of $$$. It definitely adds some. Do the math.

-Bruce
-Home Theater Intros Customized for YOUR family, on DVD: http://www.S2Digital.com

ChrisWiggles

Re: Egg cartons

Stop. You need to educate yourself about acoustics. Consult Ethan Winer's Acoustic FAQ, and purchase yourself F. Alton Everest's Master Handbook of ACoustics.

You are seriously confusing two wildly different acoustical tasks it seems. Egg cartons are usually used in-room as a sort of high-frequency diffusor, it's pretty ghetto, but it can reduce slap echoes a bit. But ugly and a big fire hazard, and generally not effective beyond just that, and not an absorber.

You are asking about isolation, however, in asking about putting them in your ceiling structure. Isolating a room is a very very different task entirely than in-room acoustical treatments. To isolate a room you need decoupled massive wall and ceiling structures, all sealed up. This is a difficult task, and must be done comprehensively in order to be effective, otherwise you can spend a lot of money building heavy wall structures, then drill out a couple holes for ceiling cans or light switches, and you've defeated everything you just built. So if you want to isolate your room, you need to really understand what you are doing, ideally with professional design help.

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