optimizing ceiling height?? Help!!

Hey guys, I'm planning on building a basement control/songwriting room. My basement ceiling height is 2,5m / 8,2 feet. Now i when I substract my floor and ceiling construction I'm left with 2,13m / 6,98 feet. Do any of you guys see a way to optimize my ceiling height within the inner leaf and keeping a decent amount of insulation?? My current composition ( option1) off materials from top to bottom is as follows. ( INSIDE OUT DESIGN) concrete ceiling: 20cm already present. airgap with acoustic ceiling hangers : 7cm (To support the ceiling ) 2 layers drywall: 3,2cm 1 layer plywood: 1,8cm 2X6 stud: 14cm inner leaf: 213,2 cm laminated floor: 1cm plywood : 1,8cm dowboard: 4cm leveling concrete: 4cm I was thinking of removing the leveling concrete out of the equation. And placing the stud wall directly on the concrete basement floor. this gives me 4cm extra ceiling height. and also smaller airgap @ceiling and heavier lumber. (option2) Basement ceiling: 20cm airgap 2cm 1 layer drywall: 1,6 cm 1 layer plywood: 1,8cm 9X3 stud : 22,5cm inner leaf 2,19cm laminated floor: 1cm plywood : 1,8cm dowboard: 4cm concrete floor : 30cm But the floor isn't verry level so gives me more construction trouble for floor and walls. Is a steel ceiling construct maybe an option? Thanks Guys for any insight and feedback!!

Allright, I did my homework and made my final design for wall and ceiling construction. finished @ 2,22 m / 7,28 feet Have a look and feel free to comment!

I did my homework and made my final design for wall and ceiling construction.

:thu: Yep! That is, indeed, the best way to do it. The only change I'd suggest making is to double-up on the joists: Because you are skipping every second joist with that plan, you are reducing the ability to support the weight. One way of dealing with that is to use larger joists that can carry the load. But another way to do that is to "sister" pairs of joists. In other words, instead of having one joist every 16", you can have a pair of them back-to-back every 24" inches, or perhaps every 36". You'll still need to check the span properties, or get a structural engineer involved. Also, instead of plywood you could use OSB or MDF, which might be cheaper and will still do the job. One other thing: Make the "modules" a little smaller that the bays between the joists, by maybe 3 or 4mm or so on each side, so that you have room to get them into place if the wood is not perfectly straight (warped, bent, etc.), or if your workmanship is not perfect 90° angles. Then fill those gaps with both backer rod and caulk, to make up the mass and get good seals, as the modules go into place. ... and you also need insulation in the air gap between the original outer-room and your new inner-room! Very important... - Stuart -

Soundman2020 wrote:

... and you also need insulation in the air gap between the original outer-room and your new inner-room! Very important... - Stuart -

Hey Stuart, The ceiling and basement walls are concrete. Do you mean I need to put insulation only on the ceiling? or also the walls? Thanks!

The ceiling and basement walls are concrete. Do you mean I need to put insulation only on the ceiling? or also the walls?

Yes! And Yes! You need to fill ALL your air cavities with insulation. Insulation acts as an acoustic damper on the resonances that occur inside the wall cavity, and the also change the way the air behaves, from adiabatic to isothermal, as well as reducing the speed of sound. You need all of those things, in both your ceiling and also your walls. - Stuart -

Ok Stuart, probably I'm getting this all wrong but. Are you saying i need to put insulation between my outer and inner wall?? and on top of the insulated ceiling? There is insulation inside the inner wall and ceiling. My idea was to build a 2 leaf MAM wall construction. My outer leaf being concrete wall then AIR and 2nd leaf my controlroom wall.same idea for ceiling. This should be right not? or am I missing something. thanks bye the way for the headsup on the ceiling joist. I'm planning on contacting an architect for the structural load calculation. Just wanted to get my basic design done and ceiling height optimized. Thanks!

Are you saying i need to put insulation between my outer and inner wall??

Yes

and on top of the insulated ceiling?

Yes

INSULATION HERE???

Yes

There is insulation inside the inner wall and ceiling.

That's part of the room treatment, but is NOT part of the isolation. It is inside the room, so it has almost no effect on the wall, which is what provides your isolation.

My idea was to build a 2 leaf MAM wall construction.

Exactly. And that is what you are doing. You have it all right, except for the missing insulation.

My outer leaf being concrete wall then AIR and 2nd leaf my controlroom wall.same idea for ceiling

Correct.

This should be right not? or am I missing something.

IT is right, yes, and you are missing something, yes. You are missing the insulation! :) It works like this: Your MAM system (more correctly called "MSM", for "Mass-Spring-Mass") is a resonant system. It is tuned, and will resonate at a certain frequency, just like all similar things, such as kick drums, for example: It's the e xact same principle: You have two membranes on a kick drum, with an air gap between them. You have two "membranes" on your wall (one is concrete, the other is drywall, but they are still membranes, as far as sound is concerned) with air gap between. In both cases, the air is a spring. When one of the membranes vibrates, it causes the air inside to compress and expand, just like a spring does. And just like a spring with a weight hanging on it, that is a resonant system. It oscillates at it's own natural frequency, which is governed by the mass of the "bouncing weight" (vibrating leaf), and by the "springiness" of the spring. A stiff spring has a higher resonant frequency, a "springy" one has a lower frequency. A lighter weight mass has a higher resonant frequency, a heavy one has a lower frequency. One way you can reduce the springiness of the air in the cavity, is to make the cavity deeper. More air is like having a longer spring. = Lower frequency. Another way you can make the spring less springy is to slow down the sound waves, which basically does the same thing: they "think" they are taking a longer path if they go more slowly, so the resonant frequency is lower. And one way you can do BOTH of those things is put insulation in the cavity: it slows down the sound waves, and also makes the distance across the cavity seem longer. Another thing the insulation does, is to "damp" the resonance: it creates resistance, or more correctly impedance, for the resonant waves as they bounce back and forth inside the cavity. It makes it harder for the resonance to resonate, because the wave meets resistance on each bounce. And that's a GOOD thing! You don't actually WANT the wall to resonate at all! It will, for sure, and it will do so at the resonant frequency, but you want to do everything you can stop it from resonating, and to drive down the resonant frequency so that it is as low as possible. The insulation in the air gap does all of that. It does roughly the same thing as the shock absorbers do on your car suspension: it keeps the ride smooth, "damping" the resonance of the suspension system. If you have ever taken a ride in a car that has the shock absorbers totally removed, leaving only the suspension springs in place, you'll understand what I'm saying... Put bluntly: if you do not put insulation in your wall cavities, it will cost you as much as 16 dB of isolation. So if you were expecting, for example, 46 dB of isolation from your wall, and you forget to put suitable insulation in there, then you'd only get 30 dB of isolation, which means your wall would have about as much isolation as a typical stud wall, in an ordinary house. Completely filling the cavity with suitable insulation can improve the isolation by as much as 16 dB. It will improve by at least 5 to 10 dB, without any doubt, even if you only fill it part way, but you get the maximum benefit when the cavity is filled with insulation. Many people get confused by the "air gap" name they see on the diagrams, and the "Mass-Air-Mass" name for the resonant system, so they assume that the cavity must be filled with air. So they get worried when they see people putting insulation in there... but without realizing that insulation is mostly air anyway! Technically, insulation is a "porous absorber", which is just air with numerous tiny fibers in it, every now and then. The fibers do most of the work, but the insulation itself is mostly air: the fibers only take up a rather small volume. If you look at insulation at the microscopic level, you see a many small fibers with large air spaces between them. Insulation is mostly air. Bottom line: leaving out the insulation will cost you a huge amount of isolation, since your MSM system will not be damped, and the resonant frequency will be too high. There's a factor in the equations for calculating MSM resonance: f0 = C [ (m1 + m2) / (m1 x m2 x d)]^0.5 Where: C=constant (60 if the cavity is empty, 43 if you fill it with suitable insulation) m1=mass of first leaf (kg/m^2) m2 mass of second leaf (kg/m^2) d=depth of cavity (m) Note the constant, "C". If the cavity has no insulation, then you need to use the constant of "60", but if you do fill the cavity with insulation, then you use the constant of "43". Do the math: 60/43 = 1.4. So the resonant frequency will be 1.4 times higher if you don't use insulation. . . .

thanks bye the way for the headsup on the ceiling joist. I'm planning on contacting an architect for the structural load calculation.

:thu: - Stuart -

Hey Stuart, Now I have a problem. On the left side of my inner leaf I need a passage for about 35cm to reach a pipe that leads to my garden house. In future It could be possible I need to draw extra cables to the gardenhouse. If I fill the cavity with insulation I am not able to reach the pipe. Might there be a way I build another wall just filled with insulation? But this becomes a third leaf so.... Or if i put ridgid insulation on the outer and inner wall and leave an airgap between them, would this be an option? I wold only do this on the wall where i need the passage. from door to pipe. the other walls I could put insulation. damn didn't see that one comming. Thanks!

Some real pictures.

Or if i put ridgid insulation on the outer and inner wall and leave an airgap between them, would this be an option? I wold only do this on the wall where i need the passage. from door to pipe. the other walls I could put insulation.

That would probably be OK, but it wastes a lot of space and makes your studio smaller. I would try to get that pipe moved, so that you do not need access to it, if possible. - Stuart -

Hey Stu, I'm not able to move the pipe. it's in the concrete wall. so.... I have a other option, and that's build my controlroom in the nextdoor room. There are also pipes but only pipesfor venting air to the outside. I'll try post a layout soon. Greets Nillis

Hey Guys, design of new controlroom and jamroom/vocalbooth. I'm struggling with the HVAC. how to fit it all in. My ceiling is way to low for making ducts inside the controlroom or jam room so I was going for ducting on the outside therefor the gap. But im searching for a way to get the cooled ait from the minisplit also into the jamroom/vocalbooth . Any ideas anyone? thanks!

I designed my rooms so that they had bulk heads running along the top edges. That might work better than cutting into your room size like you've done in your latest design. Unless my HVAC guys who are doing my house screw up my design, I was able to have 6 of the 8 silencers either between the leaves or outside of the outer leaf. 1 in each room ended up being in the bulk head/soffit in my inner leaf. As long as you maintain your surface density, it's okay to have the silencers in you room. Greg

Hey Greg, sounds like a Good idea, but i cant seem to see How this is designed exactly do you have a picture or Drawing of that design? Do you mean building the silencer inside the room and ‭the outside thickness of the silfncer would be as thick/ same mass as inside leaf of room.? In My last design the silencer is between the inner and Outer leaf. There is No option to make iT on the Outer leaf. Its a basement. Thanks!!

Ignore things like the duct corners, the fact that I don't have my inner and outer leaf supply silencers (the cluster of 4 in the middle) connected, etc. Basically, I've put a hold on my design until I see how bad the contractors who are building my house screw up my design. It's bummed me out and I've found some solace in helping other people out and just working a ton. Anyway, enough pity party. Here's what you asked for! Greg

Thanks Greg, Sorry to hear your contractors are messing things up! Tell them to F**K off! No good work no money. Thanks for the design. I'll have a decent look and see what I can come up with for my basement.

Tell them to F**K off! No good work no money.

The house builder company hires the contractors. I asked about firing them and getting different ones and I have no power. My situation sucks. Things will come to fruition soon and I can only pray that they install the HVAC and plumbing in such a way that I can make my design still work well. Greg

Hey Greg, That sucks. If work is not done propperly someone nerds to take responsabilty! Contractor or house builder. Dont take that crap!! One more question. In your design you have double silencers. One on the inner leaf and one on the Outer leaf. Is this necessary?? I Guess one on the inner leaf should do the job? Not? Thanks!!

...you have double silencers. One on the inner leaf and one on the Outer leaf. Is this necessary?? I Guess one on the inner leaf should do the job? Not?

If he did that, then there would be no isolation where the duct passes through the outer leaf... In other words, the wall cavity would be exposed to the outside world through nothing but the thin sheet metal of the duct... - Stuart -

If he did that, then there would be no isolation where the duct passes through the outer leaf... In other words, the wall cavity would be exposed to the outside world through nothing but the thin sheet metal of the duct...

He's referring to if I didn't use a silencer at each leaf penetration. Greg

He's referring to if I didn't use a silencer at each leaf penetration.

Right. I got that. And if you didn't use a silencer, then the duct itself would pass directly through the leaf. Just a leaf with a hole in it, and the duct going through the hole. Thus, no isolation. All of the sounds that occur inside the wall cavity (such as the resonances, for example....) would penetrate through the thin sheet metal of the duct inside the cavity, pass along the duct, and exit through the thin sheet metal of the duct, out into the big wide world. Conversely, any sounds occurring out in the big wide world would penetrate the thin metal of the duct, move down the duct, and exit the duct inside the wally cavity, where they now only have ONE leave to deal with, in order to get into the room... OK, so that's all hypothetical and simplified, but the effect is real. If you only isolate a duct where it passes through ONE leaf, then by definition you have NOT isolated it's passage trough the other leaf, and thus you have not isolated it. There's a clear path for sound to take through the duct, bypassing the leaf entirely. The alternative is to make the "duct" very massive (eg, a couple of layers of MDF), connect it directly to the silencer on the inner leaf and have it pass clear across the cavity and out through the outer leaf without touching it (decoupled with something soft, eg: caulk, sorbothane, neoprene, etc.). That improves the situation yes, but you still don't have good isolation: you are limited by the mass of the walls on the single silence box, since that's all that remains between the outside world (beyond the outer leaf) and the inside world (in the room itself). This is better than just having a duct going through the leaf, but still falls far short of the isolation you would achieve with a silencer on each leaf. That's what I was trying to say in my too-abbreviated response! - Stuart -

Allright, i cant build a silencer on the outside of my Outer leaf . Basement wall. So If i build a silencer on the inside of My inner leaf and one on the inside of My Outer leaf, things should be ok right?

So If i build a silencer on the inside of My inner leaf and one on the inside of My Outer leaf, things should be ok right?

Sure! The silencer itself can be on either side of the leaf, as long as it is there. Just take care to make sure it doesn't "bridge" the two leaves: no part of the silencer can touch the inner-leaf. (It's best if it isn't in contact with the outer leaf too, but that's not so easy to implement in practice) - Stuart -

Awesome im getting the idea. TO the drawing board.

Right. I got that

Stuart, I was directing that at shimmer, not you 8) hahaha Greg