Looking to sound proof a finished attic

[Tubes Horns and Buds]

Newest project is to keep the sound in my attic HT system. I am going to finish the room next month and want to keep the sound out of the rest of my house.

What would you use on the drywall (thicker drywall or insulation behind it?)

Also, is there a good flooring material to go between the plywood sub-floor and floor covering to absorb the sound??

Thanks.

[DrWho]

Is it possible to float the entire floor and maybe even build the walls on that floating floor? If you can do this, you'll have like no sound transmission at all to the rest of the house. What are the current dimensions you're working with and all that?

There's these black "roofing shingle" like rolls of stuff (can't remember the name) that are designed to be put under wood floors to help make the house less echoey and to reduce the transmission of footsteps between floors. I could experience first hand how much it reduced the sound transmission (it took us 2 years to finish laying all the wood). However, it's relatively easy to reduce mid and high frequencies (which is what this stuff does)...It's the low frequencies that are going to give you the most problems.

If you do some searching in this forum, you'll find all sorts of threads with links to other sites and all that...I don't have the time right now to provide them all now, but if you haven't found anything I'll go ahead and see what I can dig up as I know what I'm looking for.

[redtop]

Do a search on AVSForums.com for "Green Glue". It's an amazing sound proofing product. It's at it's best between two sheets of drywall or between two sheets of sub floor. I've seen a demo and I'm going to use it in the home theater project I'm starting. Highly Recommended!

Redtop

Disclaimer: I have no financial or other interest in the maker of Green Glue.

[Tubes Horns and Buds]

Thanks Guys. I will do some additional searching in this forum.

I will also check out the Green Glue for sure. I need to get this done right. I am a night owl with 3 kids.

[formica]

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On 4/9/2005 7:53:42 AM Tubes, Horns, and Buds wrote:

What would you use on the drywall (thicker drywall or insulation behind it?)

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Yes, and Yes. Us 5/8" drywall on resilient channels, an insulate the cavity.

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Also, is there a good flooring material to go between the plywood sub-floor and floor covering to absorb the sound??

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I'm unfamiliar with the "GreenGlue" but I'm assuming it acts as a decoupler. If you opt to use it, look up the STC rating gained in compositions with and without out it.

Another product with a proven history is Auralex Sheetblok which will act as a decoupler, mass loading, and infiltration reducer. It can be used for floors, walls, and ceilings.

Wood condo construction here usually use a lightweight gypsum concrete topping (like Gypcrete)... often poured on a decoupler like Enkasonic matting. Unfortunately installing hardwood flooring on this type of floor is quite tedious... but carpet is very simple.

With any of these, you should once again fill the cavity with acoustical insulation. Also eliminate any air leaks.

Note that all these methods will reduce sound transmission... but in no means eliminate it. Soundproofing is very difficult and costly... and not be attainable/required for most people.

Good luck...

Rob

[dragonfyr]

Simply using thicker drywall or covering will not stop the transmission of sound through walls. A predominate amount of the sound will be via the physical coupling of the surfaces.

The most effective wall would be a staggered stud arrangement or a double wall scenaria where the 2 surfaces are not physically coupled. Of course, you always have the ceiling and the floor to contend with in the same manner!

And mass, not covering deaden the transmission of conducted sound waves through material...

And perhaps you thought that this wouldn't be fun!

[DrWho]

But since his HT is in the attic, he just needs to worry about the floor...the sound going through the walls will just end up outside (assuming you can treat the floor behind the wall too, so that the sound doesn't go down the back). This sounds like a perfect opportunity to have a room levitated by magnets.

[dragonfyr]

Good point. I wasn't sure if there were any adjacent rooms of consequence. Well that certainly takes some of the fun out of the project!

The magnet idea sounds intriguing.

You might buy about 10,000 of the little superconducting magnet demo kits where one is suspended in air , or you could get quite a few of the Klystron magnets from replaced microwave transmitters. Just don't stick them to any flat surface where you can't 'slide' them off the side, as you WON'T be removing them for several years! And they have the additional benefit of being alot of fun to abuse, if you don't end up inadvertently hurting yourself. And in that case, they are a hoot if you get to watch the idiot playing with them who subsequently hurts himself. Been there, done that and have the smashed fingers to show for it!

On a more serious note, as the long term stability of Sorbothane isn't well known, the majority of cast cement rooms within a room that are floated utilize neoprene pucks to mitigate the transference of energy. But I suspect that you won't want to go to that extreme in the attic either.

Sounds like we won't have much fun with this thread! There simply aren't enough things to go spectacularly wrong....