Ok, I've spent a lot of time digesting sound isolation techniques and need a sounding board for my rundown of what I plan on doing. I also have a few questions.

1) staggered studded walls - These are 2x6 plates with 2x4 staggered studs at 24" OC or 16" OC?
2) 2x 5/8" + 2 tubes of GG on walls - What kind of gains does GG have when added to studded walls? The GG site leads me to believe there is little gain? Would like much more info from Ted or Brian on this one!
3) RSIC or Isomax clips + resiliant channel at 24" OC for ceiling - The GG site says this is one step under room within a room, however I've read Dennis Erksine saying don't bother if you don't do this on the walls, what gives? What should I do here?
4) Use DSC-04 clips to attach the top plate to the joists - How many do I need? Is there a calculator like there is for RSIC clips?
4) Build light boxes like Gary Kagan's or how PAC International recommends with DSC-04 clips - What do you do to seal the openings where the wires enter? Just silicone?
6) Use a solid core exterior door with good weather stripping - pretty straight forward
7) How do I seal outlets so I don't short-circuit my efforts?
8) I have soffits that run down the sides of the room, due to HVAC that can't be moved (main trunk). I obviously can't build the soffit on the inside of the room, like most, how do I avoid short-circuiting the DSC-04 damping between the top plates and the joists through the soffit framing? I assume that if I don't avoid this, I'll also eliminate the benefit of RSIC clips on the ceiling? I think a diagram would help a lot here. I just can't figure out a way to do it without short circuiting the RSIC isolated ceiling. Do I just have to settle for DD+GG for the ceiling?
9) Am I missing anything else that may short circuit my efforts?

Thanks!

For #7 - you build a drywall box, then run your electrical through the soffit and down the columns for your outlets.

#9 - how are you going to get air in your room (and out). Ducts are great at carrying noise from room to room. Unfortunately it can be tricky to address all the details in HVAC. The standard response is use ducts made of ductboards (insulated) or flex (pref insulated) and arrange for 2-3 90 degree turns. Make sure they are a bit big so that your air flows in and out slowly. I think its tricky to implement. Especially if your house works against you.

there are companies that have a 'clay' like sealer to go around the outlet boxes, after the wire is run. i would check with local building codes to see what the say about the duct work. some inspectors do not allow "s" turns in ductwork that doesn't need to be there.

some inspectors do not allow "s" turns in ductwork that doesn't need to be there
Never a problem if the duct is properly sized.

I'll talk to my contractor and see what we can do about getting some bends into the ductwork. Getting it insulated shouldn't be a problem, and during the initial showing, he said he'd have no problem separating the heating from the rest of the house. He might have also said AC too, but I can't recall. The return, I assume, would be separated by nature of the beast. I made sure to let him know that I'd like to use large entry points into the room to reduce noise, as well - I remember reading that somewhere.

I'll try and get all the gang boxes into columns. Do you just seal the wire entry point with silicone caulking?

I'm still looking for answers to #3 and #8, too. Thanks!

I'll try #3.


#3 - I believe Dennis has said in the past their is no point in making a great ceiling if you don't have good walls (and floors) to match. RSIC clips + Hat Channel + DD + GG on the ceiling matches well with Staggered Stud (decouples like RSIC, has deeper wall cavity) + DD + GG. Or at least I hope so since that is what I am building.

There is no point to having a super ceiling and ineffective walls. Back to the aquarium ... there's no point of having a leak proof bottom if the sides leak. The water is still leaking out.

Can I jump in ? - not trying to hijack this thread. I'm in same boat as OP and have the same questions. We're finishing off our basement, adding about 950 sq ft of liveable space and setting aside one room for a HT. We'd like to be able to play movies down there ( average playback level ~ 80 dB, ) without causing a major disturbance upstairs, or more succinctly, to avoid the "turn that down" comment. We have a two story house, so bedrooms are yet one more floor up. I've been reading lots of posts in this forum for several years on the various construction techniques for sound isolation and come up with the same recommendations the OP included above.

Keeping in mind Dennis's aquarium tank analogy, I think I have a problem. For several reasons ( re teenagers, concerned parents - need I say more ? ) we will not be putting a solid core door on this HT room, but rather a 5' wide glass french door set. Does that really mean whatever I do to the HT ceiling and side walls won't make any difference to volume levels heard in the room directly above ? I'm not so concerned about leakage into adjoining rooms in the basement, although I can't discount the open stairway to the upper levels either. ( preventing sound/noise from the adjoining unfinished utility area (furnace and water heater) into the HT room is something that I do need to address ). Is there still not a benefit to the room above the HT if I decouple the HT ceiling from the floor joists ?

Comments please. I sit down with the builder on Monday to finalize the bid. Clips, hat channel, GG, and extra drywall right now are part of the bid. If the extra effort and expense are negated by the glass french doors, then I'll instruct the builder to go with standard construction techniques in those areas and save myself a few thousand $.

Bill

There is no point to having a super ceiling and ineffective walls. Back to the aquarium ... there's no point of having a leak proof bottom if the sides leak. The water is still leaking out.

So staggered studded walls with DD+GG is much worse than hat channel, RSIC, DD+GG? The floor is carpet + pad + concrete, so I'm not too worried about that. Even then, my main concern is leakage through the ceiling.

I'm still struggling with #8, though. Can't quite figure a way how to have an external soffit work with the soundproofing techniques. I'm sure it can be done...

Comments please. I sit down with the builder on Monday to finalize the bid. Clips, hat channel, GG, and extra drywall right now are part of the bid. If the extra effort and expense are negated by the glass french doors, then I'll instruct the builder to go with standard construction techniques in those areas and save myself a few thousand $.

From what I read, your efforts would be wasted. If you're concerned with what your kids are doing in there alone, have you considered a video camera? That would allow isolation and still allow you to see what's going on in the room from the outside.

See here (greengluecompany.com/weakestLink.php).

So staggered studded walls with DD+GG is much worse than hat channel, RSIC, DD+GG? The floor is carpet + pad + concrete, so I'm not too worried about that. Even then, my main concern is leakage through the ceiling.

I'm still struggling with #8, though. Can't quite figure a way how to have an external soffit work with the soundproofing techniques. I'm sure it can be done...

I consider SS (stag stud) walls to be as good or better than a RSIC clip wall - if you add the DD+GG to each.

In fact look at the GG website's faq and see this:

11. Can Green Glue be used in conjunction with decoupling techniques?

Yes, and better performance can be had. For walls the preferred decoupling methods are double studs > staggered studs > modern sound clips > resilient channel. For applications where low frequency isolation is important, resilient channel is not recommended.

http://www.greengluecompany.com/faq.php

Keeping in mind Dennis's aquarium tank analogy, I think I have a problem. For several reasons ( re teenagers, concerned parents - need I say more ? ) we will not be putting a solid core door on this HT room, but rather a 5' wide glass french door set. Does that really mean whatever I do to the HT ceiling and side walls won't make any difference to volume levels heard in the room directly above ?
Bill


I'd run a search on french doors. Several people installed them. PM them and ask them the question. It could be a flanking path. You might want to pm/e-mail the GG people and ask for their comment.

If you really want glass doors to be any good at sound isolation, then you may want to consider a pair of doors in an airlock style scenario. This is assuming weather-stripping all the way around. Not sure if that's all that feasible for your layout, or if doing so would kill the benefit of having the see-trough doors in the first place.

At minimum, double-paned exterior grade doors would be a reasonable starting point.

I'll give my two cents...

1) staggered studded walls - These are 2x6 plates with 2x4 staggered studs at 24" OC or 16" OC?From what I've read, you should use 24" OC for your staggered walls. If it is not load bearing, the fewer studs you use, and the greater distance between the walls, the better.

2) 2x 5/8" + 2 tubes of GG on walls - What kind of gains does GG have when added to studded walls? The GG site leads me to believe there is little gain? I used GG and I am thrilled with the results. I don't have a non-GG comparison, so I can't say what the difference would be.

3) RSIC or Isomax clips + resiliant channel at 24" OC for ceiling - The GG site says this is one step under room within a room, however I've read Dennis Erksine saying don't bother if you don't do this on the walls, what gives? What should I do here?I think the point is that if you decouple the ceiling, you should also decouple the walls. If it is new construction, you can decouple the walls from the ceiling joists with PAC-Int'l DC-04 clips without using RSIC and hat channel for the entire wall. This is how I did my entire basement (along with GG) and I am very please with the results.

4) Use DSC-04 clips to attach the top plate to the joists - How many do I need? Is there a calculator like there is for RSIC clips?I used a DC-04 clip about every 4 feet or so. It passed my building inspections fine this way.

4) Build light boxes like Gary Kagan's or how PAC International recommends with DSC-04 clips - What do you do to seal the openings where the wires enter? Just silicone?I built light boxes (see Gary Kagan's site for details on how I did mine). I drilled the smallest hole that I could get the wire in and then sealed it with regular silicone caulking.

6) Use a solid core exterior door with good weather stripping - pretty straight forwardYep. This is pretty easy, but a very important part of your sound isolation effort. Don't forget the threshold!

7) How do I seal outlets so I don't short-circuit my efforts?There have been a number of different approaches to this. The best solution is to put all of the outlets in columns if possible. If that is not possible, some people just seal it up with standard caulking. Some people have also used an acoustical putty that encases the entire outlet. Others have built boxes around the outlets similar to the light boxes referred to above.
Brian Revnaas just posted a link in the big GreenGlue thread that suggests that outlet openings may not be a major source of sound leakage, but I would at least seal them up with caulking none-the-less.
8) I have soffits that run down the sides of the room, due to HVAC that can't be moved (main trunk). I obviously can't build the soffit on the inside of the room, like most, how do I avoid short-circuiting the DSC-04 damping between the top plates and the joists through the soffit framing? I assume that if I don't avoid this, I'll also eliminate the benefit of RSIC clips on the ceiling? I think a diagram would help a lot here. I just can't figure out a way to do it without short circuiting the RSIC isolated ceiling. Do I just have to settle for DD+GG for the ceiling?You can decouple the soffit from the joists using PAC-intn'l DC-04 clips. Here is a picture of an area in my basement and also a diagram that I drew for another forum member that may give you some ideas...

http://home.comcast.net/~scottj0007/theater/beam_hvac_rsic_copy.jpg

http://home.comcast.net/~scottj0007/theater/remi_beam.jpg

-- Scott

Thanks Scott! That was very helpful. Your diagram helped me envision how I'd decouple the exterior soffit. I'll be doing it a bit different since your diagram doesn't map 100%, but it was very helpful. Your other answers addressed all my concerns as well. Looks like I'm all set to document everything for my contractor.

This post has how I wrote my specs to my carpenters. Has details on the whole basement, so some isn't applicable, but you might find parts useful.

http://www.avsforum.com/avs-vb/showthread.php?p=9547087&&#post9547087

Scott,

That was really kind of you to produce that diagram for us. Thanks!

This is a very informative thread. I have a couple further isolation questions. I had planned on using SS walls and DD + GG for my basement theater for the 2 walls that interact with the rest of the basement. I would use RSIC clips and DD for the ceiling. For the 2 walls that are against foundation, I was just planning on putting a standard wall with 1 layer of drywall spaced 1" away from the foundation. All walls and ceiling to have insulation. My thinking was that these walls would require the least isolation, but now that I think about it further, I realize that if the sound gets through those walls, it has a pretty easy path up through the ceiling. Is there an easy way to just isolate the path behind and above those walls to the ceiling, or would I be better off spending the money and isolating those walls with clips or GG? I'm trying to lose as little width as possible, as well as being cost conscious.

Ted,

How much did that massive door cost? The STC 51 has me thinking...

EDIT: Oh, and your white paper diagrams are missing. The links go to a page with a broken image link.

Scott,
Thanks for the pics. Helpfull for me too as I will soon begin my project. A few questions about the recessed lighting mdf boxes - how are they attached to the joists and are they better, isolation-wise, than buying fixes with the sealed baffles ? I saw some 6" Halos at HD that were IC rated and were sealed.

Bill

So staggered studded walls with DD+GG is much worse than hat channel, RSIC, DD+GG? The floor is carpet + pad + concrete, so I'm not too worried about that. Even then, my main concern is leakage through the ceiling.

no, those two walls are approximately equivalent, both very good walls.

Can I jump in ? - not trying to hijack this thread. I'm in same boat as OP and have the same questions. We're finishing off our basement, adding about 950 sq ft of liveable space and setting aside one room for a HT. We'd like to be able to play movies down there ( average playback level ~ 80 dB, ) without causing a major disturbance upstairs, or more succinctly, to avoid the "turn that down" comment. We have a two story house, so bedrooms are yet one more floor up. I've been reading lots of posts in this forum for several years on the various construction techniques for sound isolation and come up with the same recommendations the OP included above.

Keeping in mind Dennis's aquarium tank analogy, I think I have a problem. For several reasons ( re teenagers, concerned parents - need I say more ? ) we will not be putting a solid core door on this HT room, but rather a 5' wide glass french door set. Does that really mean whatever I do to the HT ceiling and side walls won't make any difference to volume levels heard in the room directly above ? I'm not so concerned about leakage into adjoining rooms in the basement, although I can't discount the open stairway to the upper levels either. ( preventing sound/noise from the adjoining unfinished utility area (furnace and water heater) into the HT room is something that I do need to address ). Is there still not a benefit to the room above the HT if I decouple the HT ceiling from the floor joists ?

Comments please. I sit down with the builder on Monday to finalize the bid. Clips, hat channel, GG, and extra drywall right now are part of the bid. If the extra effort and expense are negated by the glass french doors, then I'll instruct the builder to go with standard construction techniques in those areas and save myself a few thousand $.

Bill

Bill,

Through the doors (to the room that the doors open into), extraordinary sound isolation measures will be totally wasted. Sound will leak through those doors to a considerable extent. You should still strive to seal the doors - but even with good seals performance won't be stellar.

But you said you aren't so concerned about sound leaking into the rest of the basement, and vibration/noise traveling through the structure to the rest of the house can still be dealt with effectively.


Technobabble: in a common home, all the walls in the home ar ethe same construction - 2x4's with a single layer of drywall (and usually all the same stud spacing throughout the house). The joists are similarly spaced as well, and interestingly 2x10's, 2x6's, 2x4's, and even 16" truss's will all exhibit about the same rsonance behavior at low-freqs when the wood/drywall are screwed directly to them and their spacing is the same.

So the biggest flanking path found in most houses is this:

1. imagine a theater in a basement with 16" OC studs attached to the rest of teh framework. So we have a low-freq resonance at XXXhz, and that is the weak point of the theater walls - the frequency at which the most energy enters the theater walls and, thus, the frequency range that has the most energy shoved into the structure.

2. this vibration meanders through the structure to somewhere upstairs

3. the upstairs walls ahve the same resonance behavior as the theater walls. That means that not only is the resonant region the frequency range with the most energy in the structure, its also the range that is most easily reproduced at some other place in the house. The resonant behavior of the upstairs walls will amplify this noise and...

viola, you have a situation where even 2 stories up the house might shake like crazy. That is the most devestating flanking path out there - the resonance-to-resonance trap.

/end technobabble


So anyway, structural paths could still be attenuated, and if you could put a decently sealed decently heavy door at the top of the stairs, that would really help contain the airborne sound from making its way up the stairs.

if you have a split level home or a design where the stairs don't have a door at the top, then it becomes hard for me to say whether the airborne path would outweigh everything else so much that the other efforts would be lost.

please let me know if that didn't make sense / more questions / etc.

Brian,
Thanks for the reply. I've read several of your posts in the past, and even though at times I have trouble following them, I still get something from them and appreciate your input. It's smart guys like you that draw me into this forum time and time again. :)

Anyway, about a door on the staircase. We have one of those which fold back and forth, not the straight run type. On second floor, the stairs are open with a half wall, so no place to put a door. On first floor, if we put a door on where the stairs lead to the basement, the door would either swing into the stairs leading to 2nd floor, or it would swing into another hallway. There is also a closet opposite the opening only 4' away, so that might prove awkward to open the door and not be in the way. In the basement, we will have even less room for the door swing once framing and such is in place, so the door that is currently there will be removed to allow for room to move large objects.

Bill

Speaking of resonances - if Bill decides to forgo a good sealed door on the theater, doesn't he have to treat the rest of the basement walls and ceilings with the same care as the theater room? Otherwise you have airborne sound bypassing the theater structural damping, and entering the structure through the rest of the basement? This can be prohibitively expensive (depends on basement size, obviously), much more so than a simple video camera - no?

Scott,
Thanks for the pics. Helpfull for me too as I will soon begin my project. A few questions about the recessed lighting mdf boxes - how are they attached to the joists and are they better, isolation-wise, than buying fixes with the sealed baffles ? I saw some 6" Halos at HD that were IC rated and were sealed.
BillI'm glad the pics were helpful. I've posted a full description of my light boxes and how they are mounted in this thread (http://www.avsforum.com/avs-vb/showthread.php?p=7290438&&#post7290438). I can tell you that I am extremely pleased with the performance of my light boxes, but I can't tell you how they compare to the sealed Halos by themselves. Let me know if you have more questions.
- Scott

Speaking of resonances - if Bill decides to forgo a good sealed door on the theater, doesn't he have to treat the rest of the basement walls and ceilings with the same care as the theater room? Otherwise you have airborne sound bypassing the theater structural damping, and entering the structure through the rest of the basement? This can be prohibitively expensive (depends on basement size, obviously), much more so than a simple video camera - no?

Lindahl,

you raise a really good point, and one that i've given alot of thought. In a perfect world, or if shooting for very high levels of sound isolation, the answer would basically be yes.

But... the door will reduce - even if "poor" - sound levels by around 15-20dB (thats only a guesstimate). So the sound outside of the theater will be alot quieter than inside the theater and, hence, the sound hitting the cieling and walls outside the theater will have a 10-20dB head start. Which is a pretty big head start.

So while isolation through the wall with the door will be generally crappy, and there is no question that a path of

-through doors
-through ceiling
-to upstairs

Can/will occur, 15-20dB of improvement to the theater room can still be made before this path becomes the limiting factor.

So, depending ont he level of isolation that you would need, this may be a very important consideration, but even a "poor" door with its 15 dB of isolation would give you 15dB of head-start, which does allow for considerable improvements to the theater room before it starts to compromise things.

Brian

Brian,
Thanks for the reply. I've read several of your posts in the past, and even though at times I have trouble following them, I still get something from them and appreciate your input. It's smart guys like you that draw me into this forum time and time again. :)

maybe if i really was smart, i'd figure out how to explain things really simply. :D :p i'm just teasing myself.

Anyway, about a door on the staircase. We have one of those which fold back and forth, not the straight run type. On second floor, the stairs are open with a half wall, so no place to put a door. On first floor, if we put a door on where the stairs lead to the basement, the door would either swing into the stairs leading to 2nd floor, or it would swing into another hallway. There is also a closet opposite the opening only 4' away, so that might prove awkward to open the door and not be in the way. In the basement, we will have even less room for the door swing once framing and such is in place, so the door that is currently there will be removed to allow for room to move large objects.

Bill

Bill, so a second door in the way of airborne sound isn't likely.

Perhaps you could try this experiment: make some noise where the theater will be, go upstairs to the bedrooms, and listen over in the corner of the room, then down on the floor by the crack that's probably under the bedroom doors.

Then determine if it seems like most of the noise is coming through the air (where the biggest inlet will be the crack at the bottom of the bedroom door) or just through the structure in general. Experiments like that - trying your best to determine where noise is coming from - can be invaluable.

But anyway, not being in your home, its hard to concretely state much of anything. But with a long and winding airborne path, alot of attenuation does occur, and it isn't certain that the weak door + airborne paths to the 2nd floor bedrooms will be a problem, but it is possible. I'd start by trying to feel out the situation.

Of course, if a good, well sealed, solid core door is feasible that's always ideal. :)

Brian, what is the resonance frequency of a typically well-isolated wall: DD+GG -- 6" SS + insulation -- DD? Also, what is the resonance frequency for a typical well-isolated ceiling: DD+GG -- RSIC + channel -- 10/12/16" joists + insulation -- floorboards -- pad + carpet? Not necessarily the calculated resonance frequency, but an estimate of actual resonance frequency? I realize that you probably haven't done this extensive of a test.

Also, as I understand it, GG doesn't change the point of resonance, but instead, makes it less harmful? How much, percentage-wise or dB-wise, does it help attenuate the resonant peaks? Or does it act more like a notch filter/parametric EQ?

EDIT: Oh, I should also probably qualify the ceiling as either OC16 or OC24, and the walls as OC24.

EDIT2: Also, what can be done about a typical basement concrete slab floor? I'm already tight on vertical space, so besides a floating floor, what can I do? Just acoustimat + OSB + carpet pad + carpet? Will the acoustimat and OSB help much? How much? Does carpet pad and carpet take care of the coincidence problem of concrete? For the floor, I'm only worried about transmission through the slab to other adjacent rooms.

EDIT3: This thread (http://www.avsforum.com/avs-vb/showthread.php?t=452667) is awesome, thanks a lot!

Rejoining after having to take time out for work. Gad, I hate it when work gets in the way ! :rolleyes: If only I had enough talent like the rest of you and turn this interest into a full time job.
So - good news. We're dropping the glass french doors for a double door set of solid slab doors, one side active, the other passive, on a threshold, weather stripped. That's a good start, and I figure if the weatherstripping isn't up to muster, then at least I have the ground work, so to speak, from which I can upgrade on my own. And I get them for less $$.

Scott -
On the light boxes, my builder's project manager wondered about heat buildup within it when I explained them. I thought it was a good question. I'll check out your thread you had mentioned.

Bill

...Scott -
On the light boxes, my builder's project manager wondered about heat buildup within it when I explained them. I thought it was a good question. I'll check out your thread you had mentioned.
BillSee this post on heat. (http://www.avsforum.com/avs-vb/showthread.php?p=7294343&&#post7294343)

Scott,
Nice thread on the light boxes. Clever idea that is, to suspend them on the hat channel.
Did you screw or otherwise attach the 1x2 "rails" to the hat channel ? I couldn't see any means of locking the light box assembly in place.
Good idea of using some fiber-cement siding to line the boxes. I never would have thought of that one. It's good stuff - my whole house is sided with that stuff, but we used the Owens Corning ( or was it Johns Manville ? ) brand. It's unreal how close to rough-sawn cedar siding it looks. We had a big hail storm last April with quarter-sized to golf ball sized hail. A lot of my neighbors with alum or vinyl siding had to have their siding replaced because of hail damage - not a nick on my concrete siding ! Hadn't thought of that as yet another advantage of the product. :D
Bill

Scott,
Did you screw or otherwise attach the 1x2 "rails" to the hat channel ? I couldn't see any means of locking the light box assembly in place.
BillYes, I ran screws up through the lip of the hat channel into the 1x2 rails. I didn't get any pictures of that step, but it was easy to do and held the boxes securely in place.
The cement board on the inside of the box is probably overkill, but I seem to overdo almost everything in my theater build. (That's probably why I'm still not finished after almost 2 years :eek: )
- Scott

Brian, what is the resonance frequency of a typically well-isolated wall: DD+GG -- 6" SS + insulation -- DD? Also, what is the resonance frequency for a typical well-isolated ceiling: DD+GG -- RSIC + channel -- 10/12/16" joists + insulation -- floorboards -- pad + carpet? Not necessarily the calculated resonance frequency, but an estimate of actual resonance frequency? I realize that you probably haven't done this extensive of a test.

Also, as I understand it, GG doesn't change the point of resonance, but instead, makes it less harmful? How much, percentage-wise or dB-wise, does it help attenuate the resonant peaks? Or does it act more like a notch filter/parametric EQ?

Hey lindahl,

well, we've perhaps studied the ersonance behavior of walls at low-freqs more than anybody else on the planet, and if you like i could blabber on into hours about the different behaviors, but to keep everybody from falling asleep, i'll just answer your specific qeustion. :D :D :p

with double 5/8" and normal fiberglass insulation, in the vicinity of 31 hz (+/- about 10%) is a fairly good estimate. For seperate ceiling joists you could anticipate somewhat lower values.

your comment about GG and ersonance point is a good one. GG attenuates mechanical resonances (or resonances with a mechanical component) in walls. The effect of GG varies from wall to wall and resonance point to resonance point. In same-lab, same-frame, same-insulation, same drywall & # of layers tests, GG has been shown to deliver about 6-12dB of low-frequency gains in a wide variety of walls. Looking it up real quick I have 8-13dB in a single wood stud wall (variety of tests), 10-12 in stagg studs, big gains in steel studs too. Those are low-freq gains below the STC range. At other resonances at higher freq's, it has returned as much as 20dB of gains i believe.

If you want a more detailed discussion of apples to apples GG tests, post the question in that huge GG thread and i'll get to it when time allows. I'm waiting for a plane now and posting in between breakfast. :(

additionally, the presence of high levels of damping like a GG wall greatly recudes the ability of a structure to conduct vibration. So, conveniently, GG helps one avoid the same-resonance-flanking-traip by mitigating the resonance and maiming the structures ability to conduct vibration.

EDIT: Oh, I should also probably qualify the ceiling as either OC16 or OC24, and the walls as OC24.

stud spacing will affect the location of purely mechanical resonances (like in a normal 2x4 wall), but not much effect on the primary resonance in a staggered stud or RSIC/GG ceiling.

EDIT2: Also, what can be done about a typical basement concrete slab floor? I'm already tight on vertical space, so besides a floating floor, what can I do? Just acoustimat + OSB + carpet pad + carpet? Will the acoustimat and OSB help much? How much? Does carpet pad and carpet take care of the coincidence problem of concrete? For the floor, I'm only worried about transmission through the slab to other adjacent rooms.

EDIT3: This thread (http://www.avsforum.com/avs-vb/showthread.php?t=452667) is awesome, thanks a lot!

Well, no, carpet and pad won't kill hte concrete coincidence dip. If they absorb alot of sound at those frequencies it might help, though.

There are many things that can be done with concrete, including both nothing and amazingly elaborate engineered measures. Do you have ceiling height to burn?



attached are some graphs of GG apples to apples, etc. it has to be noted that a more in-depth discussion is really needed to highlight exactly what happens in walls. For example, all walls are purely mass-defined in performance starting about 1/2 octave below the fundamental resonance.

And so forth. So if anybody wants to really chatter about it, the big GG thread is the place to go.

Scott, that picture you've attached is excellent. I have a slight variation that I am looking to get input on. I have an I-Beam that runs down the length of my proposed room. I want to put a wall along the I-Beam, and I want it to be isolated. The wall will be staggered construction. So I was planning on boxing out the I-Beam and then attaching the wall to the box. I am also planning on having a door on that wall. What would be the recommendation to isolate the wall, and still have it be strong enough for the door?

The picture linked shows the I-Beam and the Joist above.

Scott, that picture you've attached is excellent. I have a slight variation that I am looking to get input on. I have an I-Beam that runs down the length of my proposed room. I want to put a wall along the I-Beam, and I want it to be isolated. The wall will be staggered construction. So I was planning on boxing out the I-Beam and then attaching the wall to the box. I am also planning on having a door on that wall. What would be the recommendation to isolate the wall, and still have it be strong enough for the door?

I did a very similar wall that was below some HVAC duct-work with an I-beam next to the duct. The wall also had a door. Below I have attached a diagram and two pictures of the actual wall. The wall is as solid as a rock. Maybe you can get some ideas from these pics...