Green Glue, RSIC, Both? Soundproofing in General

[Otto]

Hello,

I'm working to "soundproof" pretty much my entire basement area (<900 ft^2). For now, this is going to be a general purpose area as a studio space (drums, guitars, etc.), although it may grow into a HT space in the future. Either way, I'm trying to keep sound from going into the rest of the house.

The walls are all concrete, with small windows up high. There is actually one wall that is unfinished on the basement side, and drywall on the house side. I'm going to frame all this out with a 2x6 header/footer and staggered 2x4 studs to build a staggered wall. The basement side will have double drywall and GG, and the "other" side will probably initially remain unfinished, but may get the same treatment if there's too much noise going into the house. The concrete walls will remain the way they are; I am not going to drywall them, and I currently don't care about a "fully finished" look.

I'm more worried about the ceiling of the basement, and sound going through that and into the floor of the main house. I'm pretty sure I'm going to use double drywall and GG one the ceiling install. But my primary question is this: should I also use the RSIC system? I'm only going to do this once, of course. I'm leaning away from the RSIC stuff because of 1) cost, and 2) losing headroom in the basement.

I've read threads on other forums, and I know there's a lot of discussion about GG and friends out there. Still, any comments about my particular project will be helpful. Anyone ever NOT finish the concrete walls? (not very popular for HT applications, I'm sure). Any pros who have done the same job, or same type of job, one way and not the other?

I can post pics if it's helpful.

Thanks!

[Otto]

khellandros66 wrote:

Easiest way of soundproofing a floor is to rip up the carpet and padding then remove the boards and line alot of plastic down, then fill it all with sandand staple-gun plastic over it, relay the boards and etc.

Hi Bob,

1. What kind of plastic do you recommend?
2. Any links to a particular product?
3. Would this be better than MLV?
4. What kind of STC numbers would you expect?
5. Can you cite any links to this kind of activity?

It sounds like you're suggesting to remove the carpet, pad and subfloor. I wouldn't consider that "easy", and I've done quite a bit of home improvement type stuff...

Any suggestions?

Thanks!

[Otto]

Not sure how the above post got there... It should have been over here...

[Sonnie]

Yeah... it was off topic there. You might PM Bob and let him know you asked him a question. Chances are he wouldn't see it where it was.

[khellandros66]

From my understanding sand doesn't carry sound, it absorbs it because of its physical nature, this is why many bass traps etc use sand or a similar material or sythetics to recreate the absorbing capabilities of it. This is why a number of people use it to weight down their risers for seating and use it in stages.

There are dozens of resin or polymer faoms that can be used too, however price per sq^ft. Sand is cheaper and gives good effect. The plastic would be like a strong painters plastic or heavy duty gardening plastic, both can be found at HD or Lowes.

~Bob

[AverageJoe]

I have seen examples of sand installed inside stages and seating risers, but hadn't thought about it between floors. Is there a weight issue involved, or is there just a thin layer of sand setting on the plastic?

My first inclination was to use metal channels between the ceiling sheetrock and the joists for isolation, but I'm open for other alternatives.

[Otto]

From my understanding sand doesn't carry sound, it absorbs it because of its physical nature, this is why many bass traps etc use sand or a similar material or sythetics to recreate the absorbing capabilities of it. This is why a number of people use it to weight down their risers for seating and use it in stages.

There are dozens of resin or polymer faoms that can be used too, however price per sq^ft. Sand is cheaper and gives good effect. The plastic would be like a strong painters plastic or heavy duty gardening plastic, both can be found at HD or Lowes.

Wow, I didn't even realize you were talking about using sand in between layers of plastic. I just thought there were some typos in your OP. I'd agree that sand (or, more generally, high-density mass) can be used as a deadening/soundproofing material, but I would be dubious of such an application as this. I'd definitely file this under "Experimental."

So have you ever actually ever heard of someone doing this that you can link me to? Or is this just a hypothesis? Any idea on STC numbers? (Both questions were asked in my OP). I've read quite a bit on soundproofing, and I've never, ever, come across someone recommending such activity.

Thanks!

[Otto]

Hi Joe,

AverageJoe wrote:

I have seen examples of sand installed inside stages and seating risers, but hadn't thought about it between floors. Is there a weight issue involved, or is there just a thin layer of sand setting on the plastic?

I'd suppose that if there isn't a weight issue, then you're not using enough sand. And if you're not using enough sand, then you're missing the original goal of soundproofing. If you're using "enough" sand, I would certainly be worried about the weight of the sand lying on what will likely be drywall. Also, what about the "other" stuff that's in there -- wires, pipes, insulation, etc.? And what about building codes? As above, I'd probably call this "experimental," but perhaps Bob knows something else about this procedure...

My first inclination was to use metal channels between the ceiling sheetrock and the joists for isolation, but I'm open for other alternatives.

As far as I've ever read, the RSIC clips and metal channels are an effective method. Would you also use double drywall and Green Glue on that ceiling? I think that's the best way to go. As in my OP, you see that I'm debating whether to use clips, channels and Green Glue, or just Green Glue (I'm using GG either way -- I just received four cases). I want to avoid clips due to complexity and cost, but am looking for more comments on any of this stuff!

If you're only going to do one, I think just GG (and double drywall, of course) will give you better results than just channels. Check out the GG website, they have tons of info on different materials and methods for soundproofing. IIRC, a double-drywall w/ GG setup will give an STC of 52 dB, which is pretty impressive. This varies over frequency, of course, and nothing's perfect, but it's pretty **** good.

Anyway, good luck with your project. I think I'm going to start a new thread when I start my project to post the results, as well as give me another reason to keep moving forward with it.

Have a great day.

[AverageJoe]

Otto wrote:

...I'd suppose that if there isn't a weight issue, then you're not using enough sand. And if you're not using enough sand, then you're missing the original goal of soundproofing. If you're using "enough" sand, I would certainly be worried about the weight of the sand lying on what will likely be drywall. Also, what about the "other" stuff that's in there -- wires, pipes, insulation, etc.? And what about building codes? As above, I'd probably call this "experimental," but perhaps Bob knows something else about this procedure...

Well, if there's one thing we have plenty of at the coast, it's sand , so I'm curious about the details of this method, too. I'd appreciate some more info from Bob on that.

Otto, any thoughts about how well the concrete walls will either isolate or conduct sound? I'm thinking primarily of the low frequencies.

Although I'm starting new construction instead of an existing basement remodel, I think we'll be in the same boat. I'll have two concrete walls and two framed interior walls enclosing the theater room and, like you, I'm more concerned with the ceiling than sounds traveling to the rest of the basement. I had pretty much decided to go with both methods you mentioned - RSIC and double drywall w/GG (unless it's really cost prohibitive - but I'm only doing the theater room, not a whole basement).

However, it's my understanding (someone correct me if I'm getting too carried away) that even if I get the ceiling isolated from the floor above with a RISC system, if I don't "de-couple" the walls from the floor joists above, I'll still get quite a bit of sound transferring from the walls to the upstairs floor. No problem working with the framed interior walls, but you got me thinking about the concrete walls that can't be isolated from upstairs.

I'm starting with a 9' ceiling, so I can afford losing a little headroom for the clips/channels/double sheetrock there, but I don't really want to lose the room width by framing another wall inside the concrete wall. I hope you're going to tell me it's not necessary.

Thanks in advance for any/all suggestions.

Joe

[Otto]

AverageJoe wrote:

Otto, any thoughts about how well the concrete walls will either isolate or conduct sound? I'm thinking primarily of the low frequencies.

From what I've read, the concrete walls are extremely good at NOT conducting sound. They are just too thick and too dense. I'm counting on them for 3/4 of my basement walls. I have gotten a lot of information from the dedicated theater forum at AVS and some information from the Green Glue/Audio Alloy web site.

Although I'm starting new construction instead of an existing basement remodel, I think we'll be in the same boat. I'll have two concrete walls and two framed interior walls enclosing the theater room and, like you, I'm more concerned with the ceiling than sounds traveling to the rest of the basement. I had prett much decided to go with both methods you mentioned - RSIC and double drywall w/GG (unless it's really cost prohibitive - but I'm only doing the theater room, not a whole basement).

I've done some minor research on pricing, and I think GG and the RSIC clips (not including the channel, I think) were about the same price. For some 800 sq ft, GG cost $660 shipped. I think clips were another $500+, without (I think) the hat channel. I'm still debating the RSIC stuff, but I'm primarily worried about the added complexity to the project.

However, it's my understanding (someone correct me if I'm getting too carried away) that even if I get the ceiling isolated from the floor above with a RISC system, if I don't "de-couple" the walls from the floor joists above, I'll still get quite a bit of sound transferring from the walls to the upstairs floor. No problem working with the framed interior walls, but you got me thinking about the concrete walls that can't be isolated from upstairs.

Well, as above, I've not heard of problems with this. I think it's just too **** thick and dense to vibrate enough to be able to transfer any acoustic energy into the joists of the floor above. Of course, you'd want to seal around your concrete walls where it meets your industrial-strength soundproofed ceiling system (clips, GG, double drywall, etc.) with some caulking product so nothing sneaks around. Even with new construction, will you be able to do much about the way they connect the foundation and the floor joists?

I'm starting with a 9' ceiling, so I can afford losing a little headroom for the clips/channels/double sheetrock there, but I don't really want to lose the room width by framing another wall inside the concrete wall. I hope you're going to tell me it's not necessary.

As far as sound transmission, I think you'll be OK. And I understand about not wanting to lose room width. But do you have any other reason to do it that might make it worth it? Could it be more cosmetically pleasing? Would it be nice to have it framed out so that you could have outlets all around the room, rather than concrete walls? Will it get too cold or damp down there that you might like to have insulation or moisture mitigation solutions? Oregon coast? I grew up in Eugene/Springfield, so I know it can be damp and chilly (my wife calls it bone-chilling when we're there in Nov/Dec...)

So there's some thoughts for ya. I wish I could see examples of the various configurations in action to better understand where the point of diminishing returns starts...

Have a good night.

[AverageJoe]

Thanks Otto, some good points there.

You're right about the construction. The contractor will build a pretty typical foundation and framing structure, and I'll work with what I get. He's only completing the main floor, and the whole downstairs daylight basement will be unfinished to save on labor costs. That's OK with me - I'll enjoy doing the project myself .

I like your comments about sound transfer in the concrete walls, and I'm sure you're right. I will be finishing those walls, but I was hoping to frame them with 2x4's flat against the wall instead of having a void between the framing and the concrete for isolation. It's only a few inches, but I'm trying to keep the room as wide as I can, so your points are well taken and encouraging.

[Otto]

I like your comments about sound transfer in the concrete walls, and I'm sure you're right. I will be finishing those walls, but I was hoping to frame them with 2x4's flat against the wall instead of having a void between the framing and the concrete for isolation. It's only a few inches, but I'm trying to keep the room as wide as I can, so your points are well taken and encouraging.

Sounds good. One question -- will 2x4s flat on the wall give you enough depth to mount wall boxes for outlets and switches? I think the skinny ones might fit in there. I'm sure you've already got that figured out. If you really want to go nuts on it, and you don't care too much about cost, use double drywall and GG on those walls as well. I think that would take care of any sound that could get into the concrete walls. And you'll lose less wall depth than with the clips.

Good luck and keep us posted.

[AverageJoe]

Otto wrote:

Sounds good. One question -- will 2x4s flat on the wall give you enough depth to mount wall boxes for outlets and switches?

I think I'll be OK (famous last words) since almost all switches, outlets, wiring, etc is on the opposite wall. I do need to install a couple thin boxes for surround speakers and wall sconces, but it looks like I'll have just enough clearance. I guess if I did go with a double layer of sheetrock I'd gain another 1/2" for insurance. The way I measure (Gee, I've cut it twice and it's still too short ), it's worth it.

[asolutions]

I would recommend both for a ceiling. At least with the wall if you are not happy then you have the optin of doing the unfinished side. With the ceiling you dont get that option. Also using those two products in tandem with each other is extremelly effective. You get the best of both worlds sound isolation and sound blocking.

Dave Ingersoll