Alan's rehersal space, recording studio and home theater

The more I research this project, the more questions I have.

That's a familiar feeling that I can identify with! Most people here know that feeling VERY well! So join the club... it does take a while to get your head around this acoustic stuff: you first have to un-learn everything you thought you knew, then re-learn the way it really is. Anyway, I'm a bit confused about what you are trying to do:

I was thinking on installing RSIC-DC04 clips to attach (but decouple) the tops of the basement walls to the floor joists above,

You can't do that with drywall clips! You need isolation hangers or sway braces for that. Take a look at Mason Industries. But I'm not at all convinced that you need to do that! If possible, there should be NO connection AT ALL between the tops of your inner-leaf walls and the existing joists above. Your inner-leaf walls stand on your floor, and you put new joists across the top of those walls, then hang your new drywall ceiling from that. That's the best way to maximize isolation. If you can't do that for any reason, then you would use RC on the existing joists above you, and hang the inner-leaf ceiling from that.

because of the requirements in Colorado to have floating walls

Can you explain more about that? What do they mean by "floating walls"? Probably not what we mean by that! In the acoustic sense, a floating wall is sitting on some form of spring that has been carefully selected to compress just the right amount under the exact load of the wall so that it is decoupled, and there is no longer a rigid connection: the wall can move independently of the floor. Is that what you want? It CAN be done, but is VERY expensive, hard to do right, and very unlikely that you actually need to do it.

It seems that most people hang the weight of the basement wall from the joists above.

I doubt it! You'd need really tough joists to be able to do that! I doubt that code would allow you to do that. It's normally hard enough to just hang your ceiling from the joists (if you choose to go that route), but it seems very unlikely that you would also be able to hang your walls from them. Who told you that you need to do that?

I'd assume RSIC clips are more for stabilization/decoupling between the wall/ceiling,

RSIC clips are for decoupling DRYWALL, nothing else. You nail or screw them to the joists or studs (depending on whether you are doing a ceiling or a wall), you attach the hat channel to the clips, then you screw the drywall to the hat channel, NOT to the clips, joists or studs.

What other options do I have to decouple the basement walls from the upstairs floor joists?

Simple: Just don't make any connection at all! You don't need it, and should avoid it at all costs. Your inner leaf should NOT touch any part of the existing structure. If there is some reason to do that, then you would use sway braces or isolation brackets of some sort, but the best idea is to not have any connections at all between the existing outer-leaf structure and the new inner-leaf structure. You might want to buy Rod's book, to get a better idea of how to do this right. But the basic concept is that you build your new inner-leaf stud frame on top of the concrete slab in your basement, leaving a gap all the way around. No physical contact. This frame includes the new joists for your inner-leaf ceiling. You then put insulation in the cavity, and screw/nail new drywall to that frame, perhaps also adding a layer of plywood, OSB or MDF first, if you need extra structural strength and rigidity in the wall. That's the concept. You do not need to hang your walls from the joists above. - Stuart -

Stuart, The "floating walls" that many counties in Colorado mandate are for expansive soils in the ground. Creating floating walls allows your slab to "independently" move up and down (when the soils/clay expand and contract) without impacting the rest of the structure. Basically, you are supposed to build your walls with a base plate, a 3" gap (that allows for the movement), and then the real wall above that 3" gap. Usually a nail is placed between the bottom wall plate and the base plate (a variation from the diagram that I posted in the last post, and can be seen below) that is used as a guide, so the base plate has something to follow as it rises or falls. That means the wall needs to be supported above the gap, because it doesn't benefit from resting its weight on the concrete slab. If you don't support the wall above the nail, the wall will just fall down the nail to the base plate, and your gap is gone. From reading other people's posts, people talk about "hanging their walls" from the joists to support the weight of the wall. Perhaps I misunderstood... Because of the floating floor, I don't see how I can totally build a room-within-a-room structure because those walls need some type of support structure (as the floor is not performing that duty). Maybe I'm missing something... Also, regarding the RSIC-DC04 clips that I was thinking of using, the diagram that first made we want to use them clearly shows them as being used for decoupling between the top of a wall and the floor joists above. However, I'm not sure that they can handle the entire weight of a floating wall, double sheetrock, etc...

so can you wrap the 60p nail with rubber and a rubber and metal washer under the head to decouple it more?

Unusual situation you have there! It can't be any fun to have your basement floor rising and falling all the time. My concern would be the huge weight of the walls, and the ability of the joists above to support that weight. For a wall that runs parallel to a joist, you are going to have potentially thousands of pounds hanging from one single joist! :shock: You guys must have huge, hefty joists in your floors to be able to handle that kind of load, which is in addition to the load they are already carrying. Surely there must be some structural engineer in your area that can tell you how to deal with this issue? You can't possibly be the first guy in the county to build walls in his basement. So how come the outer walls of the house itself do not rise and fall along with the floor? I guess they must be anchored very deep, in bedrock? If that's the case, then why don't they just build houses with the basement slab attached to the outer walls, but with an air space below the slab sufficiently deep that the ground can never swell far enough to reach it? - Stuart -

Glenn - Yeah, that is sort of how those RSIC-DC04 clips look/work. I think they are designed more for a wall that's weight is supported by the floor. Because of Colorado laws and floating floors, that weight must be supported somewhere else and I'm afraid that those clips won't be able to hold up the weight of the whole wall. Stuart - I agree, it isn't the most optimal situation to be in when you're trying to soundproof a basement. But really, people's basement floors aren't rising and falling all the time. It's just a precaution that some counties in Colorado have decided to adopt to prevent houses from being destroyed in those rare cases (probably from the insurance companies lobbying to have it put in place to reduce claims.) Anyway, my house is about 20 years old and not a single crack can be seen in my concrete slab. Even so, I need to follow their rules because I'm pulling a permit. And who knows, it might save my butt some day. Of course people have built out their basements, but not many try to go to the extreme lengths of decoupling and trying to build "silent" recording studios. Regarding how this potential slab/ground movement effects the outer walls, etc.... you got me! I'm still learning this stuff. :roll: So, since the weight of the wall needs to be supported somewhere other than the floor, I'm trying to figure out options other than the joists. That's why I was thinking maybe attaching the walls to the foundation wall might work, but then that is a direct coupling there as well. <sigh> I'm a musician and a computer guy, not an architect or construction worker. You're right that I might need to consult a structural engineer to help me with this problem... Anyway, your continued input is greatly appreciated. Thanks guys! Is there anyone from Colorado around here that has gone down this path?

That's why I was thinking maybe attaching the walls to the foundation wall might work, but then that is a direct coupling there as well.

I reckon you are right: the foundation wall is the way to go, but you don't necessarily need to have a hard connection there, if you don't want one! :) Thinking out loud here, and possibly way off track, but here goes: I'm thinking along two lines, with some kind of ledge attached to the foundation wall in both cases, on top of which you build your wall. (Not sure how to do that ledge, but probably just a heavy timber frame at last 6 inches wide, securely bolted to the foundation wall, a few inches above the slab, would work.) In Case #1, you'd have your "solid connection" as you said, with direct coupling, by just resting the inner-leaf wall directly on the ledge, then building the rest of the room normally as a decoupled MSM structure. You could use isolated sway braces here if you want, to get some support for the tops of the walls. That would be the easiest, and should work just fine. It would be no different than a normal build, where the walls rest no the floor, except that in this case the "floor" would be the ledge attached to the foundation wall. In Case #2 you would attach the walls to the ledge with isolation mounts. Basically floating your walls in the ledge, then proceed as above. You'd use something like this: http://www.vibration-isolator.com/ That would work too, but the calculations and the costs get a little complex. It's the same as floating a floor. Read these to get an idea of what is involved in that: viewtopic.php?f=2&t=8173 http://www.nrc-cnrc.gc.ca/obj/irc/doc/p ... /ir802.pdf I don't think you need to do that! I reckon Case #1 would be just fine for you. It shouldn't be too hard to figure out some way of sealing your already "floating" floor to the new walls. Since you say that things don't actually move much at all, probably some kind of simple flexible joint would be good enough. But having said all that, what does your local building code say about all of this? If it specifies that you have to "float" your walls, then surely there is something in there about how to do it, and how to seal walls to floors? - Stuart -

I appreciate your fast responses today, Stuart. Yeah, something like that might work. I need to read all the codes for my area to see if I can find other roadblocks or maybe even some suggestions. I mentioned it to my friend that is going to be helping me, but he said we'd need to ram-set a couple boards into the foundation wall, and he said that would be a huge pain and expensive for all the ram-set fasteners. But, if that what it takes to do it right, maybe it's worth the pain and expense. I'll try to post more once I read a bit more on all the codes. At this point, for all I know there might be some sort of code that says you can't attach directly to the foundation. :cop: (I doubt it, but then most people wouldn't think you'd have to float the walls either!)

Well, it's looking like I'm going to need to have a direct coupling between the new basement walls and the above floor joists (because of the floating wall requirements in Colorado). Because of that, am I wasting my money doing the clips and hat channel only on the ceiling? Will the direct coupling of the basement walls and floor joists above effectively short circuit or reduce the effects of the ceiling's clip/channel system? If so, is my only solution to expand the clip/channel system to both the walls and ceiling to adaquetly decouple the sheetrock from the wall/ceiling framing? If the later is the case, I'll probably need somewhere on the order of 450-500+ clips (ouch!) plus a couple thousand feet of hat channel.... and at that point it seems almost foolish to not go the whole 9 yards and do double layers of 5/8" rock and green glue, right!? Dang, this is getting expensive! :shock: .... If I was just paying for materials, that's one thing, but labor is probably going to kill me. That's why I was hoping to only do the ceiling with the clips/channel and double rock, to save all that extra labor cost, and just do regular framing/sheetrocking on the walls.... Any suggestions on how I can keep the price of this project down? From my current situation with only the rim joist insulated, I'm hoping to get a 15-20 db reduction on the outside. Maybe I'm over thinking this. Will just adding fiberglass batts between the joists and sheetrocking the walls/ceiling be enough to get me anywhere close to that 15-20 db reduction target. Any suggestions? Thanks!

While I struggle with (learn!) the macro construction details, maybe some of you can help me with different layout ideas? The attached picture is very close to the 2-D representation I posted on one of my first posts on this thread. You can see the theater area to the right. The bottom area would have been my control room, and the top area was the instrument/rehearsal area. The very top-left enclosed small room is the water meter closet, and the top-right enclosed room is the furnace and water heater utility room. (FYI - currently none of these walls or doors exist) One more thing about the diagram - The water meter closet (top-left) doesn't need to be that big. Technically it could be just as big as the door (3' x 3' ish). Would there be a benefit to opening that section of the basement up, or for symmetry purposes should I just close that whole wall up (or put a storage closet to the left of the water closet door)? Does anyone have a better layout suggestion? As I've stated before, I really like the open feel of the basement. I'd rather not make a bunch of small rooms, but maybe some walls should be moved slightly for acoustic purposes? Perhaps I should shape some of the rooms? Maybe I should shift around the purposes of the areas? To me, it seems like the theater was in the most "theaterish" part of the basement. But maybe someone has a better idea..... For reference, in relation to the diagram, my neighbors would be to the North-West and East (Assuming the top of the image is North). The closer neighbor being to the North-West.

Another option I thought of is to bisect the main length of the room, making the smaller area the control room, and the larger area the live/rehearsal room (sharing somewhat with the theater). I would have to reduce my theater to a 5.1 setup though, because the rear surrounds would need to go right where the drum set would most likely be.... :( Would that extra wall help that much to isolate the live area's sound from the closest neighbor that is to the "north west" (closest to the control room)? Or do you think that wall wouldn't make much of a difference? (Of course I realize that depends on us constructing the walls correctly, puttying the electrical outlets, etc...) Thanks again for any insight and feedback!

I still do not buy the supposed floating wall in Colorado that keeps being brought up. The idea is based on a volatile substrate which has the potential to move/ produce upthrust. Most times we have had to construct a wall lower than the existing upper floor joists to allow the floor to deflect/move. This is not uncommon, since there is always downward pressure on the upper area from either furniture (which can be arranged differently with the seasons) or persons (same thing applies) But these ideas that are trying to correct it add to the overhead load (REFER to Glenn's post) and increase the potential for overloading of the structure...it really is a simple thing and just being in Colorado does not change anything. This is an issue in many counties in many states in America in respect to the potential for upthrust or "seismic" impact. If the slab/floor pushes upward then whatever is attached directly will move upward as far as this slab/floor moves. Does this equation include a slate top pool table? If the slab/floor moves uninhibited then it will move evenly...but what if, the very likely what if we are talking about, it moves unevenly? Then the one side with path of least resistance will move quicker and rise faster and place pressure on the exterior boundary and even farther upward since there is basically an anchor on the side that is supporting the most weight which will reduce the time and rise of this part of the slab/floor. What we are dealing with is she said-he said. I have seen all the pictures on the web as it pertains to this...and they by and large are coming from people that need people...sure the luckiest people, but not the most well informed. Overloading the structure is not the answer, upheaval is not the issue. Correct information is.

Brien, All I know is, the county I live in mandates that walls be built a certain way. I'm trying to get clarification if I can make a gap at the top though. That would be much better, allowing me to truly decouple the walls from the ceiling. At that point I think I could skip the clips and channel on the walls, saving me quite a bit of time and money.... Alan

I'm trying to get clarification if I can make a gap at the top though. That would be much better, allowing me to truly decouple the walls from the ceiling.

sounds like it should be just fine! If the entire inner-leaf room is attached ONLY to the slab (which is how it should be anyway!), and then the slab does move, then who cares? As long as there is enough clearance so that nothing gets crushed, I can't see why there would be any problem. - Stuart -

Soundman2020 wrote:

I'm trying to get clarification if I can make a gap at the top though. That would be much better, allowing me to truly decouple the walls from the ceiling.

sounds like it should be just fine! If the entire inner-leaf room is attached ONLY to the slab (which is how it should be anyway!), and then the slab does move, then who cares? As long as there is enough clearance so that nothing gets crushed, I can't see why there would be any problem. - Stuart -

Yeah, that's what I would have thought too. However, almost everything I've read and looking at other people's basements, they've always done the float at the bottom. I finally found one statement digging through the county's website that claims you can do the float at the bottom or top. I'm hoping that wasn't a misprint and they actually only allow it on the bottom. If so, I'm back to a hard coupling between the wall and the floor joists above. Any comment on my other questions regarding layout, best use of space, whether adding a wall to bisect the room would really help keep the noise away from my neighbor, etc?

Ok, so I have been doing more research and think I'm closer to finalizing my plans. I'm not building the bisecting wall in the middle now (except for the furnance room wall). Otherwise, all walls will be right next to the concrete foundation walls. For the walls, I'm thinking 2x4 wood studs, 24" OC, isolation gasket tape on the bottom plate and on the face of the studs, and only 1 layer of 5/8" sheetrock on the walls. The floating walls will be built "upside down" (compared to the previous images I've uploaded on this thread), with the floating plate on the top of the wall, secured with rsic-db04 clips to the joists, and guide nails going down into the real wall. Ramset the wall through the baseplate into the concrete every 24"-32" OC. Double 5/8" the furnace wall though, for extra isolation to/from the furnance room (which won't have a ceiling). The ceiling will have isomax clips and hat channel, double 5/8" sheetrock and green glue. Caulk all floor/wall and wall/ceiling interections with acoustical caulk. The floating section of the wall will be covered by an angled "valance" or trim, made from 3/4" MDF. The valance will be strictly secured to the ceiling, and only caulked to the wall. This will allow the caulk to break and the wall to slide up the guide nails in the event I have an expansive soil problem (causing my basement walls to heave upwards - of course, this has never happened yet, but I have to build to code). My biggest question right now is with regards to weight limits. Since MDF is about 96 pounds for a 3/4" 4x8 sheet, that makes it 3 pounds per sqaure foot. So, with the valance framing and MDF, I'm guessing I'll be adding about 5-6 pounds per foot at the perimeter of the ceiling. If I double up the MDF on the valance (for more mass), that would be like adding an additional 9 pounds per foot on the perimeter. Will this cause any problems with the isomax clip and hat channel system? Should I install additional clips on the hat channel around the perimeter to be safe? I have attached a picture to illustrate the current plan... Comments or suggestions? Thanks!

isolation gasket tape on the bottom plate and on the face of the studs,

For what purpose? If that's just to get a good airtight seal under the framing, then fine, but it will not float the wall. And why would you want to use it on stud faces? How is that going to help? You cannot decouple drywall from studs like that.

with the floating plate on the top of the wall, secured with rsic-db04 clips to the joists,

I can't find any references for "RSIC-DB04", but I can find several for "RSIC-DC04" Is that what you are talking about? If so, that's not how those clips are supposed to be used. According to their web site, you would need four clips per stud, two at the top to attach it to the top plate, AND ALSO two at the bottom to attach it to the bottom plate. Their web site also says: "Note: The RSIC-DC04™ and RSIC-DC04X2™ are not designed to carry structural loads. The RSIC-DC04™ and RSIC-DC04x2™ are intended to support the loads of gypsum board and uniform loads only."

The ceiling will have isomax clips and hat channel, double 5/8" sheetrock and green glue.

Why bother putting two layers on the ceiling, with Green Glue, when you say "...only 1 layer of 5/8" sheetrock on the walls."? That doesn't make much sense. Why put two on the ceiling if you only have one on the walls?

Double 5/8" the furnace wall though, for extra isolation to/from the furnance room (which won't have a ceiling).

Once again, I don't see the logic here. Why bother putting any wall there at all if it won't have a ceiling? The issue here is consistency: You cannot isolate different sides of a room to different levels. The entire room has to be done to the SAME level. If you put two layers plus GG on all of the walls (for example), but not on the ceiling, then you wasted an awful lot of money: you would have gotten the exact same total isolation by forgetting the GG and the second layer of drywall, since the ceiling is the weak point and defines the overall total. I like using the aquarium illustration to clarify this issue: Basically, you are saying that you need to build an aquarium for your fish, but you will only put glass in the front of the frame, since that's where you need it most, and you plan to use carpet on the sides of the frame, which aren't so important, and cardboard at the back. How well will that aquarium hold water? Answer: It will hold water about as well as your room will hold sound, if you build it unevenly. You need proper glass on all six sides of an aquarium. You need proper isolation on all six sides of the room. Low frequency sound is not directional. It ignores objects that are smaller than its own wavelength, and simply bends around them. So sound that gets out through the weak "single 5/8" wall is out, and will bend around the room to cover all of the other sides too, not just that side. Sound that goes up through the non-existent ceiling of the furnace area will simply flank through the building structure, and totally ignore the wonderful 2x5/8" plus GG ceiling and wall. Isolating a room is an "all or nothing" proposition. The entire room has to be done to the same level, or you are wasting your money on the parts that you try to do better.

and guide nails going down into the real wall.

I guess I'm missing the purpose of those. Maybe you can explain how they will work?

that would be like adding an additional 9 pounds per foot on the perimeter. Will this cause any problems with the isomax clip and hat channel system? Should I install additional clips on the hat channel around the perimeter to be safe?

I think you should contact a structural engineer to answer questions like that. He needs to look at what you have, look at what you are planning to do, and tell you if it is feasible or not. Since you will basically be hanging the entire weight of the walls from the joists above, I very much doubt that you could do that safely. It isn't about how many clips or how much hat channel you put up: it is about the ability of the structure above you to support all those extra tons of weight. the only person who can tell you about that is a qualified structural engineer who examines your place carefully. But I still don't get why you can't build a simple stud frame "room in a room" that is attached ONLY to the floor slab, and does not touch the rest of the building at all. In other words, four ordinary stud-frame walls bolted to the floor, an inch or two away from the existing walls, then joists across the top of those new studs frames, resting ONLY on them, not touching the existing walls or ceiling, and with a couple of inches of clearance from the joists above. 1 or 2 layers of 5/8" drywall on everything. Done! That way, if the slab does heave, the entire room moves with it, and since there is clearance all around the edges, it would have to heave a huge amount in order to cause any damage. - Stuart -

Stuart, Yes, I meant rsic-dc04 clips - sorry, it was a typo. I disagree that I will be using them incorrectly. If you look at the attached diagram, it shows they can also be used between the top plate of a wall and the joists above (mainly to stabalize and decouple the wall from the joists). The only difference is, in my design they will be supporting that floating top plate. The entire weight of the wall will be supported by the concrete slab. The floating top plate and guide nails are just there to guide the wall (up/down the nails) as the foundation rises or falls from the expansive soils that may/may not be under my house (but required by code). I agree that they shouldn't be used to support the entire wall weight, but since the wall is sitting directly on the slab, I would think that takes most, if not all, of the stress off of the rsic-dc04 clips. I was thinking of only putting 2 layers on the ceiling for 2 reasons. #1, I can't afford the sheetrock, green glue, and labor of a second layer on all the walls right now. I'm already stretching my budget. #2, I figured it was my weakest link, since the walls are concrete. I suppose that method still leaves the rim joist less isolated though. So, I thought about adding extra mass to the rim joist area to help combat that. I see your point that it will go through the wall, and then up through the ceiling, but won't having the walls decoupled from the joists and ceiling help stop that transfer of vibration/energy? The reason for doubling sheetrock around the furance room is to isolate it more. I don't want to hear the furnace kick on when I'm watching a movie or recording. With double sheetrock on the ceiling, and double sheetrock on those walls, tightly caulked, won't that help reduce the sound from entering and exiting that room? Isn't this similar to building one awesome room next to an untreated room? If you keep the sound in/out of the awesome room, you don't need as much or any treatment in the untreated room, right? I can always add a ceiling in that room at a later date, but thought I would leave it unfinished if I can get away with it. I'm using the isolation tape under the bottom plate of the wall to get a good bottom seal across the entire length of the wall, and will caulk it to further increase the seal. Then on the face of the studs, in lieu of green glue, I thought it would help slightly damp the sheetrock from the wall framing. I understand that there will be screws going through the sheetrock into the framing, but I'd bet it works better than full contact between the studs and sheetrock without any damping at all. Maybe I'm wrong, but to me it seems like it will kill some of the sheetrock vibration. Every little bit counts, right? The reason why I'm not building a "room within a room" is because of space. My ceiling is at 7'7" at the bottom of the joists right now. There is also plumbing, ducts, a/c lineset, etc that I need to contend with. I don't want to end up with a 6'8" ceiling height. I realize that a room within a room is the best, but I don't have the space for "the best". I'm trying to get as good as I can with what my budget and what my space can afford me. The manditory floating wall design also complicates a room within a room design. The clip/hat channel/green glue/double 5/8" design drops the ceiling by less than 3 inches. It's not perfect, but it's probably my best option given my constraints. If I can get a 20 decible reduction outside my house compared to now, I'll be happy. Perhaps I'm dreaming with the current plans. Thanks again for helping me wade through these issues...