Sound Dampening - AVS Forum | Home Theater Discussions And Reviews
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Old 09-11-2013, 04:21 PM - Thread Starter
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Hello AVS wife and I just went through the process of new construction and I was fortunate to have a furnished basement which will be used as a theater. Wiring for speakers was installed but unfortunately we didn't have a chance to influence sheet-rock/insulation (long story). So the room is standard sheet-rock over blown-in fiberglass insulation...the ceiling has two "beams" that have HVAC ducts underneath and the rest is insulation. I added two pics to this post showing the before and after.

Problem is that this room is directly under the kitchen/family room. So not only does the boss say that she can hear EVERYTHING coming through the floor when I'm watching a movie, conversely I can hear people walking around and even heard the "sweep, sweep" sound of the boss sweeping the floor the other night. So...there is basically zero noise dampening either way and based on some initial research, I'd say the fiberglass insulation is likely transmitting the sound rather than dampening it!

First of all, I'm under NO illusions that I'll completely sound proof the room. That's not the intention at all...I'm just trying to add SOME sound separation. Even a 50% improvement would be huge. And I think it's just the ceiling. The walls are virtually all outside walls or walls to the crawlspace.

So, to avoid a pit in my stomach I'm trying to avoid the "what I should have done" and focus on what I can do moving forward...

Obviously there is a full meal deal solution of ripping out the ceiling sheet-rock/insulation, adding acoustic dampening material of some sort (not an expert here), re-sheet rocking and re-painting. I'm posting here in an attempt to find a solution that is not quite that extreme. I spoke with my builder who spoke with his "insulation guy" (neither are claiming to be experts) and they are saying I should explore screwing some "sound board" directly to the existing drywall then adding a small false drop ceiling (dry-walled) over that with a bit of space between. If something like this would work, it sounds like a cheaper/easier solution than ripping everything down, but I wanted to get some feedback from the experts here. Thoughts on solutions? Thoughts on materials to use?

Appreciate any feedback!

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Old 09-11-2013, 05:20 PM
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Don't have time for a lengthy post. Just start at and do some research. Lots of good info on how to clip and channel a ceiling and then add double layers of mass with a damping agent in between. That is your best bet. Of course sound can get to your kitchen through many flanking paths as well.
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Old 09-11-2013, 08:12 PM
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If you want to add material to the ceiling, you can so that - but I wouldn't recommend doing what I understand your builder to be suggesting. The addition of an air cavity in the partition may improve the situation at some frequencies of sound, but may also make it worse at others. I would say that if you are considering adding drywall, I would just add another layer. You might also consider pulling up the floor in the kitchen and adding a underlay, like Serenity Mat, which could improve the footfall noise considerably.

Grant is right, of course, that there are lots of other likely routes for the sounds to be transmitted. Unfortunately it is seldom as simple at the single partition between two spaces needing improvement - generally, a holistic approach is required. And while the blown in insulation is probably contributing to the transmission, I suspect that decoupled drywall is really the best choice. Sorry.

Call the guys at and have a chat with them. They can help you decide if it's worth it.
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Old 09-12-2013, 07:29 AM
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And I think it's just the ceiling. The walls are virtually all outside walls or walls to the crawlspace.

This seems to come up quite often. The fact that the walls are outside or to a crawlspace (or whatever) really doesn't matter. They are ALL tightly coupled to (i.e., tied into) the floor joists above and will transmit sound.

If you are willing to go through the process of adding a second layer (or two if I'm reading it right) as recomended by your (obviously) non-expert builder/insulation guys, why not just tear down the ceiling and do it right? Either way, you have to tape and mud.

+100, talk to Ted at soundproofing company.

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Old 09-13-2013, 12:01 PM
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Originally Posted by tlogan6797 View Post

If you are willing to go through the process of adding a second layer (or two if I'm reading it right) as recomended by your (obviously) non-expert builder/insulation guys, why not just tear down the ceiling and do it right? Either way, you have to tape and mud.

Yeah, I agree. I hate to say it, because I totally sympathize with the o/p, and he's probably freaking out about the costs of tearing down everything he just built and starting over (never a good position to be in). However, I recently built my own home theater directly underneath a kitchen much like this, and I started with the same problems of sound transmitting between floors. I could actually hold a conversation with my wife when I was in the basement and she was in the kitchen without either of us raising our voices. Having gone through that, I can tell him that the only way to do this is to do it right and address sound isolation from the beginning with two layers of drywall decoupled from the walls and ceiling, and dampening material between the layers.

Sound isolation is unfortunately an all-or-nothing proposition. You can't have "just a little" soundproofing. Sound is like water; it goes everywhere and gets around everything. You need to plug all of your "leaks" or you might as well give up and not do anything at all.

I'll give another +1 to all the suggestions of talking to The Soundproofing Company. They will put you on the right path.

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