John Sayers' Recording Studio Design Forum Archive

I'm currently in the process of designing a drum room in my basement. I might eventually try my hand at recording as well. My goal with the room is to be able to play while the family is home and not annoy them.

The basement has poured concrete walls and the ceiling is about 93 inches tall, so I don't have much height to work with. In the 5 years I've lived here I've never seen water in the area where the room will be. The room will be a room within a room. The outer room will be 12 feet by 14 feet. The inner room will be 10 feet by 12 feet and the ceiling will be about 80 inches tall.

I attached pictures of the basement where the room will be and detailed drawings of the walls and ceiling. I also included the acoustic treatment I plan on using in the drawings There will be 4" thick base traps using Roxul Rockwool 60 in all 4 corners from floor to ceiling. There will also be 2" thick acoustic panels on 2 of the walls using Owens Corning 703 that are 2 feet by 4 feet in size. I'll also be using 2 solid core doors, but I left those details out of the drawings.

I'm looking for any advice you might have as to what I could be doing wrong or could improve. I don't plan on starting the project until September so I have some time. My budget is around $2000 and I'll be doing all of the work myself.

Hi there " MotoX244", and Welcome!

I'm looking for any advice you might have as to what I could be doing wrong or could improve.

From what I can see in your diagrams, you are planning to build "a room in a room in a room", with four-leaf ceiling and four leaf walls! That's going to take up a lot of space, cost a lot of money, and be far less effective at isolation as compared to normal two-leaf construction.

If you look around the forum a little, you'll see that two-leaf walls and ceilings are the best way to isolate a room for the least amount of money, and least amount of materials. A three-leaf system will always isolate worse than a 2-leaf system (all other factors being equal), and a four-leaf will be even worse than a three-leaf or a two-leaf.

I'd urge you to just go with a standard 2-leaf "room in a room" build: it will save you time and money, and use up a lot less space.


- Stuart -

Thanks for the feedback. I'll definitely make a change to the ceiling so that the existing upstairs floor is one leaf and the inner room's ceiling will contain the second leaf. So i'll be tearing down the existing half inch drywall that is already attached to the 12 inch joists.

My detailed diagram for the walls might not have been clear. There are 2 types of walls, one type that goes against the concrete and another type that will be free standing. So I want to say the walls are already two-leaf.

Here is rev 2 of the room. I think the walls and ceiling are now two-leaf.

Here is rev 2 of the room. I think the walls and ceiling are now two-leaf.

That's looking better!

Except that with wall #1, you need a gap between your concrete wall and the inner-leaf framing. The gap doesn't need to be large, but big enough to ensure that there's no physical contact between the framing and the concrete.

You could gain another three inches of acoustic ceiling height by building your ceiling "inside-out", instead of conventionally. It's a lot more work, but when room height is at a premium (as it always is for home studios!), then it's worth the effort. Ans ESPECIALLY for drums! Drums like large rooms with high ceilings.

Also, if you want to maximize isolation, then consider completely filling the entire cavity between your leaves, with insulation. Don't leave any empty air in there. This sometimes confuses people, since the see reference to the "air gap" between leaves, but in reality that air gap needs to be 100% filled with insulation to maximize isolation. When you think about it, insulation is mostly air anyway, so it is still an "air gap", even when it is full of insulation.

And speaking of air gaps, why did you choose an empty space of 3.75" between the two frames of your wall #2? It probably isn't necessary to leave such a large gap, unless you already did the math and came up with the conclusion that you do need it.

- Stuart -

Thanks again for the help, here is rev 3. I added a gap in wall #1 and decreased the gap in wall #2. I also added more insulation in the ceiling.

I needed to make the gap large in wall #1 to make room for a water pipe that comes in and out of the room. I wanted to keep the top half of the pipe behind the drywall. I'll have to make a special section for the bottom half to be accessible from inside the room.

I tried to find a way to move the inner room's ceiling joists into the existing ceiling joists like you suggested, but nothing really worked. There are ducts running in the joists that get in the way. I more than likely would have to switch from 2x4" joists to 2x6" joists as well because they will need to run 12 feet instead of 10 feet. 10 feet is already pushing it for using 2x4" joists.

I do have a question about the ducts in the ceiling, is there any good way to help soundproof them? I'm sure that will be a path for noise. Would blocking them off with drywall be bad because it becomes a three leaf system? There is only a couple of joists with ducts in them. I attached an image of where the ducts run.

I think I didn't clarify what an "inside-out ceiling" is, so let me explain:

An "inside out" ceiling is not built the way you imagined, with the ceiling joists interleaved with the floor joists above: that's nice in text books, but seldom works in practice, for the reasons you mentioned: ducts, water, sewage, gas, electrical, structural, etc. So I don't try to do it that way, because the gains are too small to make it worthwhile. An inside-out ceiling is built with the sheathing on top of the joists, not under it. That maximizes the acoustic height of the room, without changing the height of the joists themselves, which really can't be moved much anyway. But what matters in a studio is the acoustic height, not the aesthetic or cosmetic height of the ceiling, and that's where you get a major advantage from "inside-out", because the full depth of the joists is INSIDE the room, not outside of it.

And speaking of joists, the dimensions of the joists are only really relevant for a conventional ceiling, such as the one you propose: they are irrelevant for inside-out ceilings, for the reasons I give above: The joists bays are inside the room, not outside it, and thus are part of the acoustic height and hte acoustic volume of the room. In a typical room, that adds hundreds of cubic feet to the room volume.

Yes, you are right; 2x4 joists are way undersized to span 10 feet with the type of load we are talking about: unless you could get Red Maple select structural joists (or some similar unusual and expensive wood), you'd be out of luck for that. I normally end up using 2x8s for studio ceilings. Very occasionally I manage to use 2x6s for small rooms, but sometimes it's necessary to use 2x10s even, especially if the cieling also has to carry the load of the HVAC silencer, which are heavy, and a ceiling cloud, which is heavy, along with the other common loads on a studio ceiling. For your 12 foot span, I would suggest at least 2x6 for a either type of ceiling, or perhaps 2x8, depending on what wood species you are planning to use.

Anyway, with an inside-out ceiling, you do things backwards, and upside-down (as the name implies).

You start by building a "backbone" of properly sized framing members, dimensioned to support the ceiling correctly, as in the photos below. This comes from a studio that one of my clients built in Australia a few years ago. I'm showing this specific case because it is similar to yours: this client not only plays and records drums in his room, but he also teaches drums: so he frequently has TWO drum kits going full-bore in there, and his neighbor's front door is just a few meters away from the studio door. With the completed studio, the neighbor can't hear a thing, so I reckon you could say that this system works!

So this is the first step: Build a framework of large dimension joists, that have to carry the rather high weight. Instead of being spaced at the normal distance, they are spaced wider apart and "sistered":
From that photo, it looks like they are touching the floor joists above, but in reality they aren't: there's a gap of about an inch up there.

The next step is to build "modules" that fit into the empty spaces between the backbone framing. Each module is just ordinary 2x4 framing (perhaps even 1x4, or 2x3 in some cases, since each module is small) with as many layers of sheathing as you need. In this case, I designed the ceiling with a base layer of 1" plywood, and a top layer of 22mm fiber-cement board, with Green Glue in between. It's a drum room, so I needed to maximize mass, damping, and rigidity all at once. This was the combination that I came up with.

You build those modules flat on the floor, then raise them into place, like this: As you raise each module, you caulk the sides of the framing abundantly, to get a good air-tight seal, then you screw/nail/bolt the module to the backbone framing. You raise it as high as possible inside the cavity, so there's just a small gap between the top surface of the sheathing, and the bottom of the joists above.

In this specific case, we needed extra assurance that we'd get maximum mass continuity and maximum sealing, so there's actually a "lip" on the top of each hole, and the module butts up against that, with abundant caulk. So there's both a vertical and horizontal surface for it to mate to: Here's a view of the ceiling with almost all of the modules in place except for the last one, which is just going in, in those photo: Notice that in this studio, the walls are also built inside-out, for the same reason: maximize room volume.

Next, you fill the joist cavities inside each module with suitable insulation (the type and density depend on what your goal is). You hold it in place with some form of simple strapping, or mesh: even chicken wire will do the job. In this case, we used nylon packing strapping. Then there's a layer of black plastic tight-weave mesh, which does several things: it prevents loose fibers from filtering down from the insulation, over time, and it also prevents over-absorption of high frequencies from the deep insulation, as well as helping to keep the insulation flat (so it does not cause sagging and bulging in the finish fabric layer), and it also prevents light getting through, so you can't see into the ugly insulation. The lower layer is some type of nice breathable finish fabric: it can be whatever you want it to be. For this room, the client chose a light beige color, so it looks more like a normal drywall ceiling. Other people lie to make bold statements with strong colors in their fabric. That's a purely aesthetic decision. Not acoustic.
Here's a view of about half of the ceiling done: And the last section of fabric going in: Then we added thin wood trim to hide the staples that hold the fabric in place: ... light fixtures (wiring an inside-out ceiling is dead easy):
The finished room: And time to make music! So that's how you do an inside out ceiling. In this case, I used the gaps between some of the floor joists above for the HVAC silencer boxes and ducts, so that they would not take up space inside the room itself:
Of course, that was before we started with the ceiling!

In other words, we used every last possible inch of space for something, and ended up gaining 6" of acoustic height, and over 120 cubic feet of room volume. Actually we gained more than that, because with a conventional ceiling we would have then needed several more inches of acoustic treatment below the drywall, so we would have lost another 6" of visual height like that, so the final aesthetic ceiling would have been another six inches lower than what you see here. With an inside-out ceiling, the acoustic treatment is mostly built in to the ceiling itself and you don't need anything below that.

It's pure advantages, with the only disadvantage being that it's a bit more effort to build. But the results are very much worthwhile.


- Stuart -

It took awhile for me to wrap my head around what an inside-out ceiling is but I finally figured it out. A very creative way to gain space, but it like you said, would be more work building.

I spent some more time trying to get the floating ceiling to work and I think I figured it out. Only 1 joist goes through a duct, so I'll get a 12" joist just like the existing joists and route the duct through the middle. It looks like the other 3 joists should be good using structural grade 2x6" lumber.

I'm still a little concerned with the ducts being between the two leafs. I saw some adhesive sound deadening material that I could wrap the ducts with, like you would use in a car to deaden road noise. I'm not sure if it would be worth the effort/money though.

I'm still a little concerned with the ducts being between the two leafs. I saw some adhesive sound deadening material that I could wrap the ducts with, like you would use in a car to deaden road noise. I'm not sure if it would be worth the effort/money though.

You have to "box in" the duct work. It makes a 3 leaf system but it's pretty much the best way to deal with mechanical.

Greg

You have to "box in" the duct work. It makes a 3 leaf system ...

Exactly. And in this case, that would trash the isolation because the gap between that and the inner-leaf would be very thin, implying a very high resonant frequency, likely well into the mid-range.... thus destroying practically all of the gains from attempting to isolate the ceiling at all. Yet another reason why I never do ceilings like this, with interleaving. If you do the ceiling inside-out, it's a piece of cake to modify the modules under that 3-leaf section so that the gap is much larger: plenty big enough to get the MSMSM resonance down low enough where it won't be a problem.

If anybody feels like doing the math to calculate the resonance from this issue, here's the equation:
It's not that hard to do. I don't have the time to do that right now, but I can predict the result: lousy!


- Stuart -

I could probably move some of the ducts to add space. Would moving the ducts as close to the top leaf as possible then building an enclosure around it with 1 or 2 layers of 3/4" plywood be a good compromise? Something like the following.

I could probably move some of the ducts to add space. Would moving the ducts as close to the top leaf as possible then building an enclosure around it with 1 or 2 layers of 3/4" plywood be a good compromise?

Yes, but if you have any registers that poke up through the floor, you'll be out of luck trying to get the elbows to reach properly as they have a fixed radius. Also, you'll quickly realize that fixing the wood to the bottom of your sub floor as you've drawn in your picture is more complicated than your drawing. You'll also need to leave space for adequate damping within your box. What I mean is that you'll need to leave 2-4" around your duct work to stuff (lightly without compression of course) insulation otherwise your box will ring like a drum.

Lastly, to more accurately answer your question, you'll need to answer your own question by doing the math (or using the MSM calculator on the forum) to determine:
1. what type and how thick of material you need to build the box out of
2. if in fact you can maintain your MSM isolation with the distance the bottom of that box will be from the top side of your inside out ceiling module.

Like Stuart pointed out, it's pretty easy to have a lower modules in the areas where your boxing is causing your MSM gap to be too little. It may in fact require both moving your duct work up AND lowering certain modules. You could beef up the modules and/or the box material to help with this as well. You'll need to do the math to figure out exactly how to resolve the issue.

You're not alone though. Most people on the forum have dealt with very similar issues as you. I'm one of them and that's why I built the calculator. I hope it helps to speed up your process as it did mine!

Greg

Thanks for making that calculator, very helpful. I think I'm going to go back to my original idea of using 2x4" joists right below the existing 12" joists. Hopefully that gives some decent results for the 3 leaf system under the ducts which will be about 1/4th of the ceiling. I thought about doing the inside out ceiling, but it seems like a bit more work than I'd like to do. I'm more concerned with soundproofing so I can at least play my drums. If the acoustic quality suffers a little, I'm ok with that.

I do have another question, do I need to be concerned with the sides of the 12" joists surrounding the ducts? Is adding a layer of 1/2" OSB and 5/8" drywall going to help much?

I'd suggest boxing in the duct by just resting a material on the top side of the bottom 2x4 on your I joist. That way you are able to fill the cavity with insulation while utilizing that extra 1 1/2" of space. It's also really easy to rest the material up there.

I think I'm going to go back to my original idea of using 2x4" joists right below the existing 12" joists. Hopefully that gives some decent results for the 3 leaf system under the ducts which will be about 1/4th of the ceiling. I thought about doing the inside out ceiling, but it seems like a bit more work than I'd like to do. I'm more concerned with soundproofing so I can at least play my drums. If the acoustic quality suffers a little, I'm ok with that.

The thing is, the acoustics in that room will suffer a lot more than "a little" by not stuffing your inside out ceiling with insulation. It's your room, time and money so obviously you can do what you want but I don't suggest doing it the traditional way.

I do have another question, do I need to be concerned with the sides of the 12" joists surrounding the ducts? Is adding a layer of 1/2" OSB and 5/8" drywall going to help much?

I just brad nailed 3/4" MDF to the sides of my joists. I figured out using the calculator that that combination would maintain my needed surface density. I did put green glue on as well.

Greg

I think you convinced me to try the inside out ceiling. I'll see what I can come up with. Thanks!