"Cork is better than rockwool" true?

[212121]

Hi, I had to re-build my living room and bedroom because I live in a really hold house. I'm not building any studio but I asked them to put some isolation in the ceiling because I can hear my neighbor walking. I told them to use rockwool, that's what I hear everyone talking about, so they are using 4CM rockwool and I hope that when they finish I will not hear my neighbor.

I asked them what they knew about acoustics and if there was anything else I could do in my room. I asked if rockwool was the best and they told me that cork was (really) better, I tried to search the forum but didn't find much info

It's sad that I don't have the money to build a small studio at home, but at least i'm going to isolate the floor and ceiling, it's better than nothing!

Thanks

[naethoven]

Here's a little bit of info I know. Sound can be transmitted (ie: from your neighbors to you) in two ways: airborne sound, and structure borne sound. Airborne transmission happens when sound waves hit a surface (neighbor's floor), the surface flexes, and the sound is reproduced on the other side (your room). This can be solved by adding MORE MASS to the ceiling in the form of another layer of drywall, and by putting insulation between the wall surfaces. Rock wool is great for acoustic treatment inside a room, but in a wall the regular fluffy pink stuff works just as well and probably costs less. Sound goes anywhere air goes, so any time you build something for sound, it must be airtight construction. Caulk everything with non-hardening caulk/acoustic sealant.
Structure borne transmission is sound carried through the solid structure of the building. For an example of this, put your ear on an end of a 2x4 and have someone LIGHTLY tap the other end. You will see that you can hear it very well, even louder than you can hear it in the room through the air. This is also known as flanking. The way to deal with this is through decoupling the structure somehow (resilient channel, "shock absorbing hangers" (I forget the real name), room-within-a-room design (recording studios use this)). I don't have my reference book infront of me but this is all I can remember off the top of my head. Keep researching

[andrebrito]

Cork are rockwool are used for different purposes and applications...

[nosebleedaudio]

Look at how a WELL designed isolated floor is built, to really make a difference it's similar to a wall ect...
But in this application cork or sheetblock or rubber pad will help.
If it's in a rented building then it has to be easily removed, and the above example might fall under that category...
I have the same problem where I live, hardwood floors above me; I can tell exactly where the guy is...

And sound is heard via 3 means; straight from the source, reflected or coupled thru the structure.
And ALL of the above..

[shangoe]

dont know in what density the cork product has you are talking about. but think about this: to absorb something, it has to be conducting air. i dont think cork is doing that.

[Weasel9992]

I think what the OP is talking about is reducing noise transfer from one floor to another, in which case cork would be effective to some degree if it's thick enough. I'm assuming you mean a cork layer between the floor and the joists, of course. You could also fill the cavities between the beams in the ceiling with mineral wool or rigid fiber glass and that would give you a bit more reduction.

To really do it right would require a near total rebuild of the ceiling/floor though. As the other posters have stated already, you'd need to add mass and incorporate decoupling techniques to have any profound effect.

Frank

[naethoven]

Hey,
I posted earlier, but I was kind of in a hurry to go to work. To simplify, I personally think your best bet would be using RC-2 (resilient channel) to hang 2 layers of 5/8" drywall from the rafters. The cavities behind the drywall would be filled with normal batt insulation.

You need to be as sure as you can to make sure NO PART of the ceiling touches the rafters directly or indirectly through another rigid material (ie: wood, drywall, nails (not even one), screws, etc.). Do NOT pack the batt insulation tightly. Some will tell you to do this, but if you do, you create a rigid member and effectively connect the drywall ceiling to the rafters. This will ruin the isolation you are trying so hard to achieve. The only things that are allowed to touch both the drywall and the rafters are non-hardening acoustic sealant, the RC-2, and very lightly the insulation.

If you decide to purchase resilient channel, BE SURE that you are actually getting RESILIENT CHANNEL. It looks very similar to Hat Channel and other types of ceiling track, but it is not the same! The others absolutely will not work, they do not isolate and all your work will be in vain. Also, be sure to get RC-2 and not RC-1. 2 is for ceilings while 1 is for walls. You need RC-2 to support the weight over your head!!

About the drywall. I don't know what your budget is/how much isolation you want, but the rule is more mass=more isolation. (the rule is not as "effective for the $/work/loss of space" after about 2 or 3 sheets.) One sheet by itself would help a little (because of the resilient channel), and if it is thicker than the drywall on the ceiling now even better. If you can do 2 sheets you will definetly gain a lot more.

Reply with any questions!!!

[taturana]

the floor part is easy.. in my studio i used a thick conglomerate board on top of 30cm of styrofoam plates... the whole structure floats on top of the styrofoam and the edges of the wood do not touch the walls... it cost me some 400 dollar parts and labor without the wood flooring itself..... but labor here where i live is cheaper..

works perfectly...

[212121]

Thanks for the replies