I need some opinions from people with first-hand experience regarding soundproofing. I've done tons of research and I'm still stuck. Here's the story. I live in a brand-new condo building. Of course, the builders didn't build the walls and ceilings to code so there's sound leakage. The good news is the building is under warranty and they're planning to either fix it or simply reimburse us for costs to fix it. So here are the two possibilities I'm considering for the theatre room:

1. Add two more 5/8" sheetrock layers to existing structure with 1 tube of Green Glue (50% coverage) per 4x8. These layers would be screwed through the original sheetrock and into the studs/joists.

2. Use Isomax sound clips, furring channels, insulation, and 2 layers of 5/8" sheetrock layers over existing structure. I know this usually is a no-no as it causes the dreaded triple-leaf effect, but the Isomax site shows this as an option. Plus, the airspace between the existing and new will be small and filled with insulation.

The two options above are for the ceiling and flanking walls will have an additional layer of 5/8" with Green Glue regardless of which way we go with the ceiling.

The goal is to kill as much impact noise as possible as that's the real culprit. I guess the real questions are if the using clips over the existing structure is acceptable (triple-leaf and all) so long as the air gap is small and full of insulation. And what the performance difference between these two options would be as the 2nd costs twice as much due to the clips, furring channels, and insulation. Any thoughts would be appreciated. Thanks!

Any option to remove the original drywall? Clips are great if attached to the framing. You mention the small air cavity being perhaps not such a big issue due to it being small, but being small is exactly the problem

We have a large motel chain out west that built their walls, then added resilient channel, then drywall. You can hear the person dialing in the room next door. We would never have received a call if it weren't for the improper resilient channel application. This is an active job for us, but over the last 4 years I have been involved in literally dozens of projects, large and small that have been compromised by that darned little air cavity. Both clips and channels. Furring strip also.

The problem with it is that due to the small volume, it resonates at a very high frequency... right in the vocal range.

So regardless of whose site shows this as an option, it is definitely not desirable, and could make things worse.

Thanks Ted. Removing drywall isn't completely off-the-table, but we'd prefer not having to do it as it'll make a mess obviously. From what I understand, DD and GG will yield good results, but clips directly to the joists is superior. How big a difference are we talking real world?

Ted would know best, but not sure any of these approaches are best for impact noise. The usual first solution I see in condos is carpet.

From what I understand, carpet will stop sounds from coming down, but will not stop bass sounds from our unit going up.

How is bass (LFE) going up "impact noise"?

If you are asking about LFE, GG + more mass is a good solution, and probably easier than ripping out drywall to properly install clips.

The goal is to kill as much impact noise as possible as that's the real culprit.

You mentioned impact noise as the real problem, which would typically be foosteps from above. You also mention this theater, which sound going a different direction.

Is removing foorstep noise from above actually the prime directive? Or containing your theater?

Instead of removing the drywall, could you just cut several large holes in each stud space to eliminate the triple leaf effect.

Instead of removing the drywall, could you just cut several large holes in each stud space to eliminate the triple leaf effect.

This is a great thought.

Theoretically at some level, yes. The question would be how many holes. There would be some progressive curve. More holes makes better performance.

I suspect you may have to remove quite a bit. However, if you had the basic requirement that the drywall could not be removed, obviously throwing some holes in there is better than not. We just don't know how much better.

You think new construction on top of old is not going to make a mess? Think again! What about all the old outlets that now need extended? What about the new drywall that needs sanded making a huge dust bin of your house?

deconstruction just requires a bigger dumpster is all... - the costs of deconstruction are likely saved with other things being easier - and will give you properly built performance.

Is removing foorstep noise from above actually the prime directive? Or containing your theater?

I'd say removing footfall noise from above is a higher priority.

Cutting holes in between the studs seems as much work as removing the entire drywall.

I'd say removing footfall noise from above is a higher priority.

Cutting holes in between the studs seems as much work as removing the entire drywall.

Consider adding drywall and damping material applied to the underside of the subflooring above. Imagine removing the ceiling drywall. You'll be looking at the subfloor above. Apply drywall to that.

Then R19 fiberglass. Then clips and double drywall below. that's the best you could do.

Thanks for the suggestions so far.

Ted, are you suggesting I cut drywall to fit between the joists and attach that to the subfloor above? Would I screw straight up in this case or somehow attach it to the sides of the joists? I'd have to remove the current fiberglass insulation in this case and reinstall afterwards. Would this make any difference as the joists are what carries the vibrations. Am I incorrect?

Also, how large a difference would clips with DD and GG be vs. going with DD and GG over the existing ceiling?

You have that exactly right. Add mass to floor above and damp the mass. SCrew through drywall into subfloor to anchor. No precision cutting, fast.

Reinstall fiberglass.

This will damp a great deal of the footfall vibration, meaning less vibration available to enter joists. Less of a workload for the ceiling below.

This may all sound odd, but it works very effectively, and is about the only way to treat the vibration at its source without installing pads / etc. on the floor above.

Seems the way to go then is to do as you suggested and add drywall with GG to the subfloor, reinstall insulation, install sound clips and furring channels, and screw a layer of 5/8" drywall to the furring channels. If that's not enough, add another layer of 5/8" drywall with GG. I assume regular metal screws is all that's needed for screwing the drywall into the furring channel.

This might be considered overkill by the builders so I may have to incur the cost of removing drywall. What's the average rate (per square foot) these days for a contractor to come out and remove a drywall ceiling? Also, does it matter which clips are used (Isomax, PAC, etc.)?

I'm not sure about labor to remove drywall. That would depend on a few things. Nailed, screwed, glued, loose insulation above vs. batts.

Clip considerations: http://www.soundproofingcompany.com/index.php?/products/clips They're all good.

If I were going through all of this, I would have them install a second layer of drywall to the clips system. Drywall is cheap at $8 a sheet and hanging is about $0.20 a sq. ft. The added weight to the resilient clip system will be a big deal.

I'm surprised the RSIC-V yields almost as good as the other clips considering there's no rubber. Or is there?

The current ceiling is as follows: subfloor, joists, insulation, wood furring channels, and 3/4" drywall (screwed).

I may actually hire someone locally to do the work and send the bill to the builders. I might even do some of it myself. We're working on details now. You guys don't have anyone in MA by any chance do you?

No rubber on the RSIC-V. This lessens the damping, especially in the low frequencies. However, clips decouple great and damp very moderately.

Let a damping material damp, and a decoupling material decouple.

So you would suggest:

1. Attaching drywall with GG to the subfloor above.
2. Use RSIC-V clips.
3. With the money saved by using RSIC-V, go DD and GG on the furring channels.

My only concern is that the RSIC-V won't provide the low-frequency benefits. But you think with 2 layers of drywall (3 really when including the drywall attached to the subfloor), it should be enough? I see the RSIC-V clips are a third of the cost of the RSIC-I. I guess I'm having a hard time understanding how the RSIC-V decouples if it has no rubber and gets fastened in a hard way to the studs.

One other thing. I know that building code requires that walls in condos, hotels, and other multi-dwelling buildings be at least STC 50 and IIC 50. Does anyone have links to these codes online or are they only available in the hardcopy books? Thanks!

Hardcopy of building codes are available at local building officials office. Also at library. Not online, as the books are bought.

The clips + channel introduce some resilience, which is where the benefit is obtained. The small amount of rubber damped a bit.

The low frequencies (and all others) will be improved significantly with double drywall and Green on the Hat Track.

This combination makes for a really excellent low cost system.

Thanks Ted!

I can head to the local library or town hall. Am I looking for the ICC code book?

IBC = International Builders Code Any local codes all use this as a basis. Your local group / state may call it slightly diffrently, but the library should know.

Well, it has been months and things have been moving at our condo. The unit next door to us is empty so has served as a test unit these last few weeks. Walls were done using 5/8 and Green Glue so hopefully that'll do the trick. For the ceiling, they went against what I had suggested which was to remove the existing ceiling and use Isomax clips. Apparently there was some kind of fire assembly issue when they discussed it with the Kinetics folks so they went with RSIC-1 Retro clips over the existing ceiling. They also ran the furring channel parrellel to the joists due to spacing which I don't understand as both 24" OC and 16" OC can add up to 48" OC required by clips. Sure enough, it didn't sound like anything improved in that unit at all. I'm sure as hell not going to let them do our unit that way. If anything, I think I'd rather they put 2 layers of 5/8 with GG up if retro clips are the only option.

You are 100% correct in your assessment. Clips are great for decoupling, but NOT if there's a small air cavity created. We sell PAC clips but never the retro.

I am not aware of any building code that prohibits the use of clips on open framing. These products have been tested by UL in full scale wall / ceiling burns.

Just out of curiosity, would running the furring channels parallel to the joists really make a difference? I imagine the rigid attachments are still far less.

No difference

I have some more details. The joists are 24" OC and there's wood strapping running perpendicular to the joists at 16" OC. Apparently, the wood strapping is party responsible for keeping the building in one piece so removing it may not be an option. Would it still be worth cutting holes into the ceiling along the joists and wood strapping and then going with sound clips and a new ceiling? Or is GG the only solution in this case?

A picture would help, but you could still proceed and install clips next to the strapping. I imagine the protruding clip would clear the strapping.

Getting the decoupling from the clips is a significant step, so I continue to encourage it.

Unfortunately, I don't have any pictures as our ceiling is intact. Based on what you said, it sounds like you have a pretty good idea of what it looks like. Thanks for the help!

One more thought, I was thinking of paying out-of-pocket to have them upgrade the clips to spring isolators like the Kinetics ICW. The Kinetics website shows they have a 10 point STC advantage over the regular Isomax clips. How realistic is that figure?

The Isomax is a good performer, for sure. I'd have to look at side by side data to see if the ICW had any significant isolation advantages that couldn't be explained by having a deeper cavity, etc.

One thing, with the 1.5" of gypcrete on the floor, you're going to get some big STC test numbers. That's what I saw over on their site.

There's only so much improvement in STC you're going to get with any clip or suspension system. The real area we see big gains and differences with clip systems are in the low frequencies and of course STC doesn't measure this.

I don't think you'd see a 10 STC point difference even comparing a clip system and a completely decoupled floating ceiling. And we know that the floating ceiling is superior, though not practical for most.

This would be especially true if both the clip ceiling and the floating ceiling were heavily damped. The difference would really be relegated to the very low frequencies.

I think I'll have them go ahead with the spring isolators as it'll only cost a few hundred bucks more which I don't mind paying out-of-pocket. It'll be worth it if there's a gain the lower frequencies and I'll only get this chance once. For the walls, I'll probably go one more layer of 5/8 and GG. My wife and I were thinking of doing a couple of stone walls for aesthetic purposes. I imagine that'll help block noise as well.

Are you still considering removing the existing drywall and beefing up the subfloor above?

Curious, how much ceiling height do you have to deal with? Could you consider a floating ceiling? It's without a doubt the most decoupled of all options. No clips, no channels.

Yes. I'm pushing to have the drywall removed. If I have to do it myself, so be it. I would cut along the joists and strapping to create pieces that I could use in the subfloor above. I would then remove the remaining pieces and screws.

The ceiling is 8'3" right now which includes the 3/4" drywall. Inside the ceiling are trousses (I think that's what they're called) which are 24" deep. What do you mean by a totally floated ceiling? I thought using clips created a floated ceiling?

Something else I was considering was tearing the drywall off the shared walls and putting up a new frame making a double-stud wall. The current walls have studs 16" OC wood so I was thinking of going with steel or wood studs at 24" OC in the new wall. There's only a couple outlets to move and I think I'd be willing to give up the space. But I have no clue how to create a wall like this as it seems to be it has to get attached somewhere.

What you are describing has the makings of sound isolation far greater than what you were initially thinking. A true room within a room.
http://www.soundproofingcompany.com/index.php?/library/articles/room_within_a_room

Decoupling is not an all or nothing proposition. You have degrees. Clips decouple, but a double stud wall is completely decoupled. Cheaper and more effective than clips.

The same holds true for your ceiling. Inserting new framing into the ceiling will allow you to attach drywall to a surface that does not contact the existing framing at all.

This new framing would be held up by the new inner walls you described.. This would also address flanking coming through your walls. http://www.soundproofingcompany.com/index.php?/library/articles/flanking

If you can do this it will be less expensive than clips or isolators and much more effective.

If I understand, you're basically saying to reframe each room with the exception of the floor. Most rooms would allow me to put up a double-stud wall on the two long sides only. Would that be enough to hold the structure up? In some areas, there are doors, closets, and windows so it'd be tough to get a structure up there. And obviously, I couldn't do this in the narrow hallways.

I'm assuming this would amount to loss of space all around, but I'd be living to live with that. I'm surprised you mention it would be less expensive as I would have thought hiring a carpenter to come out and reframe and entire area would cost more than using clips. Also, would using steel studs cost much more? I'm thinking they'll take up less space and be more resilient just by their nature.

P.S. I'm going to take some pictures of what our place looks like so it'll help.

Doing the two side walls will work to hold up floating ceiling.

Doorways can be accomodated with extension jambs if you like.

You can also consider modifying existing 2x4 walls to make them staggered 2x5 walls. Decoupling achieved with a 1" loss of wall space.

Wood would be easier. The resilience isn't an issue once totally decoupled.

Thanks

Thanks for your help Ted and your patience. This stuff is all new to me.

With the floated ceiling assembly, I assume you screw drywall directly into the new frame above? No clips, hangers, nothing...

Staggering the existing common wall could be an option, but I would think studs in place now would have to get moved and such. I have no idea what a carpenter costs these days so in your opinion, would modifying say a 10' wall with the ceiling height I mentioned earlier cost less and be more effective than simply adding multiples layers of 5/8 and GG? Also, am I correct that staggering the current walls doesn't help the ceiling situation as it's part of the old structure?

No problem, glad to help!

Look at that article and you'll see the floating ceiling diagram. The new framing does not contact the existing, and the drywall is 100% secured to the new framing.

Just a thought, not sure about the straps you mentioned earlier. They would have to be considered.

The old wall studs do not get touched at all. We simply weave in new ones.

This might be easier if I spoke with your contractor as well.

I have no idea what a carpenter costs these days so in your opinion, would modifying say a 10' wall with the ceiling height I mentioned earlier cost less and be more effective than simply adding multiples layers of 5/8 and GG? Also, am I correct that staggering the current walls doesn't help the ceiling situation as it's part of the old structure?

Introducing this simple method of decoupling with two sheets of damped drywall would be much more effective than simply adding 2 additional layers (3 total) of drywall and GG. Second option = more Green Glue, bit is not better.

The staggered walls helps the ceiling situation because it deals with flanking noise that started in the ceiling. It also allows you to attach the floating joists to the new staggered framing members.

Much of what I'm talking about is above and beyond what the homebuilder is willing to do. They're only required by MA code to hit STC=45 and IIC=45. I'm looking for overkill and willing to hire my own contractors to do it. As it stands now, they're willing to install additional drywall on the common walls with GG and RSIC clips with a single layer of 5/8 on the ceilings. I'm trying to find a way where I can hire my own people to do some work, but not affect the work they need to do. With the double stud option, they still have to attach drywall to a frame, lower sprinklers, etc... It actually creates less work for them as no clips or furring channels are needed. With the staggered approach, I'm not sure this is still true.

One last consideration I have. My wife was thinking of installing surface-mounted track lights on the new ceiling, but if we go with an entirely floated ceiling with its own structure, how much of an impact would recessed lighting have on the soundproofing? I assume only some air-borne transmission would get through as the ceiling would be completely de-coupled.

Try using the small diameter lights that are 3 1/2" diameter. Keep the number of them small and the diameter small and you'll be OK.

is it that necessary to do light boxes? i don't mind making them if they improve, however im not sure if they meet code by building them out of mdf. any tips on this?

If you have many lights, or large (standard) diameter larger than 4", you should consider boxes.

I recommend outer box of OSB so you can glue / screw into a box. Then inner layer of cement board. Use sealant in corners.

okay, i may try that. ted, i've been searching for hours and can't seem to find the answer. i will be doing 1 wall with dd and gg on both sides. i believe the stc rating for this is 55-56 (according to your website), assuming 2x4. if i were to make this wall a 2x6 staggered construction again with dd and gg on both sides, what is the stc rating? and, in terms of dc-04 clips does it matter which way the rubber gets mounted to? (ie. walls, ceiling, etc.) thanks again.

Hi Anthony. Staggering obviously introduces decoupling, so you get another world of goodness as a result. Likely mid to high 60s, assuming some fiberglass in the wall and using double 5/8" for the mass advantage. Much better LF performance!

Two walls (poured concrete) of my basement space are shared with neighbours (sandwiched townhouse). I was thinking of a hanging my decoupled ceiling on supports directly fastened to these walls. Then simply finishing those same walls by laminating drywall to their surface.

Any negative thoughts as far as sound transmission/reflection from those poured walls...? I'm thinking it doesn't get much more dense than 10 inches of poured concrete. Really... i was more concerned about reflection.

What do ya think...?....suggestions.

Hanging a header on the foundation and installing a floating ceiling? That the idea? That will work.

You have to be very careful about attaching drywall to concrete. A small air cavity will significantly lower the isolation that foundation provides. The air cavity will amplify higher frequencies. Very well documented by the NRC in Canada.

So either finish the wall with no air cavity (insulated or not) or create at least a 3" insulated cavity. There is no issue relating to the massiveness of the wall and the quality of the sound within the room.

Hanging a header on the foundation and installing a floating ceiling? That the idea? That will work.

Yep exactly... Thanks

A small air cavity will significantly lower the isolation that foundation provides. The air cavity will amplify higher frequencies.

Stud wall it is then. For the small amount of sqft loss it's worth not worring about.

Very well documented by the NRC in Canada.

Boy you're not kidding. http://index.nrc-cnrc.gc.ca Search engine is fantastic...!

I'm in process of getting estimates from carpenters and just making sure I get all my questions out. If I want to convert the existing walls to a staggered configuration, is there any reason steel studs couldn't be used? Or are those tougher to cut requiring a double stud configuration?

Stick with wood. Can't really mix the two systems.

sorry ted I did thank you some time ago for your reply... Had to wait for a mod to check my post... (big brother is watching...lol)

....hmmm why did this one pop up right away?

You're welcome of course. I think you're past 5 posts now.

While you're right here I might as well ask. If I do attach a header to the poured walls, it won't technically be "decoupled", so dispite the fact it's a foundation, is LFE a concern to my above floor and neighbours?

What do the top plates on the new wall attach to? As I understand it, when building a new wall, you screw the bottom plate into the floor and the top plate into the ceiling. In this case, screwing into the ceiling would eliminate the decoupling. Is the bottom plate enough to hold up the walls and new joists without any support from above? I assume yes based on the links Ted provided in an earlier post.

http://www.soundproofingcompany.com/media/rsic-dc04/rsic-dc04_datasheet.pdf

thats a great question. i too am contemplating which method would work best for strength and decoupling when attaching a floating ceiling. the link ted provided explains a lot, as well as his entire website.

just out of curiosity, what methods are available for using the dc-04 clips when making a floating ceiling? specificially, if the next joists rest on the walls, would it be okay to attach the new joists to the existing joists or will this negate somewhat the floating ceiling soundproofing? im not sure what other ways one can attach the walls with dc-o4 clips and do a floating ceiling. any advice or pics on this ted?

http://www.soundproofingcompany.com/index.php?/library/articles/room_within_a_room

Generally the new joists rest on the top plates on the inner walls. The inner wall's top plate is generally what is attached to the old joists with the DC-04.

sorry, i should have been more specific. actually i will be running my new joists perpendicular to the existing ones because i need to drop down the entire ceiling from hvac supplies as well as the joist span. i can see how it is done if one runs the joists in the same direction as the existing ones, but what about if they are perpendiciular and about 1' lower?

You would / could attach a ledger board to the inner walls. The new joists attach to this board, typically with joist hangers

http://www.soundproofingcompany.com/media/rsic-dc04/rsic-dc04_datasheet.pdf

That was the missing component. Thanks!

I've had a few contractors out over the weekend and today and think I'm closing in on solutions. It looks like installing new ceiling joists will prove too difficult so using the existing structure is the only option. Here's my plan:

Walls:
-Add 5/8" drywall with GG to existing wall (homebuilder will pay 100%).
-Demo current drywall and install either staggered studs or sound clips (homebuilder will do final drywalling without GG).

Ceilings:
-Demo current drywall (leaving wood strapping in place) and install ceiling spring hangers. I know they cost a few bucks more than say the RSIC-1 or Isomax, but they do have one big advantage. They'll allow the ceiling to stay at pretty much the same height. For a few hundred bucks, I figure why not opt for spring hangers. Not sure if the homebuilder will do the demo yet so I'm getting quotes to have my own contractors do it if necessary.

Things are moving along and I've been negotiating with the homebuilder. Here's where things stand now:

Ceilings-
Complete demolition of existing drywall and wood strapping. RSIC-1 with 2 layers of 5/8 drywall and GG.

Walls-
Additional 5/8 drywall with GG.

I think this is as good as I'm going to get without spending a large amount of my own cash. Hopefully we'll be moved out soon and the work will be done by the end of the year and I will report back results once I'm living back in our unit for at least a week. I'll also try and take pictures afterhours while the construction is going on.

Re hangers versus clips--Ted White suggested to me in another thread that clips can be placed on small 2x4 blocks that are then tacked up into the joists (along their sides) such that very little ceiling height is lost. Something to consider if there is a real cost difference.

Lots of cables have a code number (like E135174A) that can be traced back to the manufacture & specs.

Hey Guys,

Here is that pic that shows the use of Blocking with Clips and Hat Channel to conserve headroom.

http://www.soundproofingcompany.com/upload/SPC_Blocking_RSIC-V_HC_Med.jpg

Things are moving along and I've been negotiating with the homebuilder. Here's where things stand now:

Ceilings-
Complete demolition of existing drywall and wood strapping. RSIC-1 with 2 layers of 5/8 drywall and GG.

Walls-
Additional 5/8 drywall with GG.

I think this is as good as I'm going to get without spending a large amount of my own cash. Hopefully we'll be moved out soon and the work will be done by the end of the year and I will report back results once I'm living back in our unit for at least a week. I'll also try and take pictures afterhours while the construction is going on.

Just when you think things are going your way, an inspector comes along and ruins it. The building inspector nixed removal of the existing drywall due to fire assembly violation. I guess MA is stricter when it comes to condos and fire code so I'm stuck with the existing strapping and drywall. What are my options at this point? Their plan is to build over the existing structure using RSIC-1 clips which I know isn't going to work well as I've heard it first hand. What's the best thing I can do to supplement this structure? I was thinking having 3 layers of drywall with Green Glue (or 2 layers of QR510 to save space) on the furring channels or perhaps just adding 3 layers of drywall with Green Glue to the existing ceiling without clips. I'm confirmed the ceiling will handle the weight. Another options is to use the RSIC-2 clip which increases the air gap to 2 inches. Any help would be appreciated. Thanks!

That's a bummer. Avoid the clips as you last stated, Just add as many layers of drywall and GG as you can manage.

The small air cavity will be bad as you've heard firsthand

Thanks again Ted!

Construction starts on Saturday! The plan is to add 2 layers of drywall with GG to the ceiling. The inspector asked that the architect give it a once over to be sure the ceiling doesn't come crashing down killing us.

The work has been completed and we had no choice but to let them use clips and drywall over the existing ceiling. They did use light insulation in the air space and I had them add a 2nd layer of drywall with GG.

The GG hasn't fully cured yet as it has only been about 3 weeks, but the noise has reduced in our unit which I credit the extra drywall and GG since the noise has not improved in all the other units which did not have the extra drywall and GG. Although the footfall noise isn't gone, it is more bearable now and I find that I'm not obsessing over it anymore.