Building a recording space in a brick warehouse

[blunderfonics]

Hi Everyone,

In the next week or two, I will be starting construction on a new recording and rehearsal space in an old electrical supply warehouse. The rough dimensions of the room are L:29’ 4” x W:20’ x H:11’ 8”. I intend to divide the space into a Tracking Room, Control Room and a couple small Isolation Booths to be used for tracking guitar/bass amplifiers.

The bands I usually record are of the LOUD variety. Since this is a rehearsal space I don’t worry about disturbing the neighboring spaces. The other side of that coin is that I can fully expect that there will be quite a racket going on outside my walls at any given time. Because of this I would like to concentrate on isolation on the interior perimeter in hopes that I can record as much as possible without having to schedule around my neighbors.

The room is on the ground level of the building, on a concrete slab. As such, I don’t think I want to attempt floating a floor but may need to do some kind of raised floor in the control room as the slab is not quite even and level in that corner and I wish to put down some sort of laminate flooring to make things look nice.

The outside walls are 1’ thick solid brick, as is the interior brick wall shown in the floor plan. The stud-walls on left side of the room (as shown in the diagram) will be constructed by the management of the building, as will the partitions that enclose the 2 openings on the interior brick wall (bottom). In other parts of the building he has been doubling the frames between rooms, stuffing them with pink insulation and applying one layer of sheetrock. He has agreed to add an air-space between the double walls of my room but it will be up to me to add additional layers of sheetrock.

Ceiling height to the bottom of the joists is 11’ 8”. The ceiling Joists are 2” x 10” (full dimension), roughly 14” on center running parallel to the shorter side of the room. There are large steel I-beams crossing the room in both directions. Sprinkler system plumbing, electrical conduit and fluorescent lighting are all currently suspended from the ceiling. On top of the joists there is a tongue and groove sub floor and hard wood on top of that. There will likely be rehearsal spaces on the second floor above me.

The ceiling is my main concern as I hope to isolate my self from the drums and amps sitting on the floor above, but the sprinklers and I-beams restrict the ceiling design possibilities. The tops of the sprinkler heads are about 4” from the bottom of the joists, so suspending a ceiling below the joists is likely to be out of the question. I’m guessing my best solution is to simply apply layers of sheetrock directly to the joists.

My Budget is around $3000 for the initial construction. I have good friends who are willing to pitch in labor (including a licensed electrician), so hopefully that budget can be entirely used for materials (barring the occasional pizza and beer order to keep the workforce happy). I am planning on using steel framing because the overall increase in cost is outweighed by the increased ease of transporation and installation

Questions:

1) Can I achieve a good amount of isolation from the rooms above by simply stuffing the joist cavities with insulation and adding layers of sheetrock?

2) What is the best strategy for adding mass to such a ceiling? Is it worth the extra work to add a layer or two of sheetrock to the bottom of the floor between the joists or would I be better off adding that mass as another layer on the bottom of the joists.

3) How much mass can I add? I haven’t seen any span tables or calculators that deal with full dimensional lumber and the odd joist spacing. Do I need to worry much with the steel I-beams carrying the weight of the ceiling?

4) Will the interior brick wall offer enough isolation or will I need to beef it up? I found somewhere that a 1’ solid brick wall would have an STC of about 65, but I’m concerned about it’s performance in the low end.

A gallery of photos of the room in it's present state can be found here and SketchUp files of my layout can be found here:

http://www.ampsvsohms.com/studioconstruction/

[knightfly]

1) Can I achieve a good amount of isolation from the rooms above by simply stuffing the joist cavities with insulation and adding layers of sheetrock?

Not likely; the sprinkler pipes and heads will flank sound everywhere, especially if you're required to leave them operational (as in, sticking THROUGH your ceiling)

2) What is the best strategy for adding mass to such a ceiling? Is it worth the extra work to add a layer or two of sheetrock to the bottom of the floor between the joists or would I be better off adding that mass as another layer on the bottom of the joists.

Both. However, we will need more info to determine whether this is feasible; if your actual unsupported spans are 20 feet, you're screwed. I plugged dressed #2 and better 2x10's on 12" centers (close to what you have, yours is probably a bit better) and came up with only 30/10 loading for a 20 foot span. If your I-beams break that up into shorter lengths, cool... Also, you'd be miles ahead if you can beef up between existing joists and then build a SEPARATE frame for the inner ceiling; much better isolation than trying to do it all on the same frame.

3) How much mass can I add? I haven’t seen any span tables or calculators that deal with full dimensional lumber and the odd joist spacing. Do I need to worry much with the steel I-beams carrying the weight of the ceiling?

See above; if, as it looks, your I-beams cut the span down to about 10 feet, then weight-wise you're in good shape. However, there's still the question of those (*&#*sprinklers...

4) Will the interior brick wall offer enough isolation or will I need to beef it up? I found somewhere that a 1’ solid brick wall would have an STC of about 65, but I’m concerned about it’s performance in the low end.

Straight mass law here, it's STC 65 but comes in at 37 dB @ 50 hZ, linear increase to 65 dB @ 500. Add a frame and 2 layers of 5/8" gypsum with the wallboard-to-brick distance at 8", and you'd end up around STC 95 with 53 dB @ 50 hZ, m-a-m resonance around 30 hZ.

Now, about those sprinklers - Steve

[blunderfonics]

Thanks for the reply Steve.

The main sprinkler pipe is hung down from the joists so that they are just low enough to get under the I-beams. The sprinkler heads then extend upwards towards the ceiling to approximately 4 inches from the bottom of the joists.



I’m not sure whether code requires that I leave the sprinklers functional or not, but I assume that the Fire Marshall would want me to leave them exposed. I haven’t been able to sift through the code to find out the exact requirements for such a situation. My landlord was unsure that the code requires but has given me the wink to do what I want after inspection IF I wanted to enclose them. I’d rather not do that in the live room if at all possible. Apart from the potential hazards and code violations, totally enclosing the sprinkler plumbing in the ceiling would lower my ceilings down to about 9' which would eliminate most of my storage space (hanging lofts that double as acoustic clouds) and bring the ceiling closer to my overhead mics than I would like. As I see it, I’d be trading one problem for another.

My current design already calls for 2 of the sprinkler heads to be enclosed in the ceilings above the Control Room and above the Booths. I believe that I can skirt the code in this situation because of the size and of the rooms and their ‘intended use’, but I need to do more research. Hopefully isolating the Control Room and the Booths in this manner will help me towards the goal of doing at least doing some overdubs when my neighbors in the building are rocking.

The two solid brick walls (top and right sides of the floor-plan) are exterior walls of the building. The nearest neighbor from any of these walls is hundreds of feet away, so I think these walls should be fine as they are.

The interior brick wall (bottom of the floor-plan) has two large openings which the landlord is going to fill with a doubled stud-wall and sheetrock. I’ve asked him to leave an air-gap between the studs so that when 2 layers of sheetrock are added to the studs the faces come flush with the brick. The opening that falls in the Live Room is likely to be where my entrance door is. This will be a double door affair, but that means totally closing this wall off is out of the question. In any case, I’m not sure that I can beef up this wall significantly as it would eat into my floor-space and budget, creating a 3 leaf situation at certain points along the way. With the corridor on the other side of this wall, I don’t see this being the place where I need to spend the money. I don’t think it would be impossible to add this wall later if this turns out to be weak link. As I see it, the common wall between the spaces (left of floor-plan) and the ceiling are the most likely to be problematic and the most likely to improve significantly with the right game-plan. Tell me if I’m off-base here.

Thankfully the I-Beam that runs the long way across the room carries the ceiling joists and it’s pretty beefy (16”x8”). For all intents and purposes, it is located in the center of the ceiling (but is actually a few inches off center). There are 2 other I-beams that are perpendicular to the large one. These have 2x6’s laid on top of them so that they come into contact with the joist that runs just above. There is also a C-shaped beam running parallel to the main I-beam, about 3 inches from the outside wall (top of the layout drawing - however, I’ve neglected to include the C-beam the SketchUp). There is some wood on top of this coming into contact with the joists as well.

So it would seem that I have enough structure to carry quite a bit of weight. Using your substitutes of “dressed #2 and better 2x10's on 12" centers”, a 10’ span can carry a 100/20 load (this span calc doesn’t allow for dead loads greater than 20 lb/sq.ft.). Does this mean that that mean that I could theoretically add 5 layers of 5/8” Sheetrock @ 2.6 lbs/sq.ft/layer to the current dead load on the ceiling joists, if we assume that the floor above me is 2 layers of ¾” Plywood @ 2.3 lbs/sq.ft/layer (it’s not, but I’m guessing it’s roughly the equivalent)?



Questions:

1) Have I got the sequence of materials for the ceiling correct? Could I be adding more mass somewhere? Should the layers be distributed differently?

2) Should I add Resilient Channel, Green Glue or, dare I say, Mass Loaded Vinyl into the ceiling mix? Because of the proximity to the sprinkler heads I might have to give up a layer of Sheetrock in order to fit the profile of the RC. Is this the one situation where MLV becomes a viable alternative or is it just too darn expensive to ever have a good cost/benefit ratio? Do any of these offer a better bang for the buck in this application over adding a layer of sheetrock?

3) Is the flanking through the sprinkler plumbing more likely to be caused by them coupling with the ceiling via the rigid hangers that suspend them, or from sound from other areas of the building hitting the pipes directly and flanking into my room? Would suspending them somehow semi-rigidly help? What about wrapping them in pipe insulation and/or insulated duct tubing?

[knightfly]

Your drawing looks good except for needing resilient mounts/channel below; I'd go with RSIC clips and hat channel for three layers of drywall. From your description it sounds like you have more than enough to support the weight, unless your upstairs neighbors decide to float a 4" concrete floor above you

No MLV necessary, just resilient mounts to decouple from the upper floor.

Flanking is tough to figure even when I'm phyically THERE; but using padded mounts on the pipes will help damp them somewhat. Also, any place the pipes go through the wall or ceiling they need to be kept away from contact or padded with neoprene or butyl (preferably)

If the pipes are in the room instead of above the drywall, they'll flank mids and highs into adjacent spaces(and vice versa) - you can improve this by running several beads of BUTYL caulk (better damping) along the pipes and wrapping them with rigid fiberglass if they're in the space with you. I've no idea how effective this will be, only that it will help... Steve

[blunderfonics]

The addition of RSIC clips and Hat Channel to 3 layers of 5/8 sheetrock would bring the total thickness of the ceiling to 3½ inches from the bottom of the joists. This would bring it very close the tops of the sprinkler heads. I worry that this could potentially be a recipe for disaster with unskilled labor (namely: me).

How would it affect the overall transmission loss of the ceiling if I forego the RSIC Clips and moved one layer of mass to the bottom of the floor and used normal Resilient Channel or Hat Channel and 2 layers of Sheetrock under the joists?

[knightfly]

RSIC's can actually use LESS headroom than RC if done correctly - you run the hat channel PARALLEL to joists and fasten the clips further up into the joist bay. if the clips interfere with the joists, you can mount them to blocking placed BETWEEN joists and RECESSED enough so that the bottom, attaching portion of the hat channel is only 3/8" or so below the bottom edge of your joists... Steve

[blunderfonics]

RSIC's can actually use LESS headroom than RC if done correctly - you run the hat channel PARALLEL to joists and fasten the clips further up into the joist bay.

Cool! I hadn't thought of that.

Would this be using the RSIC-1 EXT04 clips or standard RSIC-1's somehow? I'm having a hard time visualizing how you would use RSIC-1's without some form of blocking.

if the clips interfere with the joists, you can mount them to blocking placed BETWEEN joists and RECESSED enough so that the bottom, attaching portion of the hat channel is only 3/8" or so below the bottom edge of your joists... Steve

I suppose if I ripped a 2x10 to 7 1/2" wide, I could use it to to block up the sheetrock under the floor and provide a place for the RSIC clip to screw into. Is there any problem with this?



Would I need to pay any special consideration to the fasteners that hold the blocks in place as essentially they would be carrying the weight of the 3 layers of Drywall?

[knightfly]

That's one way, but easier if you just get 2x6 and nail it between joists at the height it needs to be for your installation. This block would be such a short span, even a 2x4 would work; but a 2x6 allows 3 nails per end without fear of splitting. That way, you can still get insulation over the top of the block.

You could also build a temporary "spacer" consisting of a short section of hat track in a RSIC, with a board screwed to the track - then, at joist spacing, you could fasten 3/8" spacers on the TOP of the board - then, when inserting your blocks you'd hold this spacer against the bottom and push up til the outer spacers touch the joists, and nail the block. Sorta like...

[blunderfonics]

Update: Well, it’s been a couple weeks since my last post and construction has started on my new room. There has been a change of plan with the building: Another studio has taken the space on the other side of the brick wall at the bottom of the original floor plan. This has both good and bad ramifications for my space.

The good is that instead of three rehearsal rooms with 2 bands apiece, each blasting away 2 or 3 nights a week just outside my space, I now have a neighbor who will only be tracking full bands a couple days a week and doing overdubs the rest of the time. Obviously, he has a mutual interest in achieving a good amount of isolation between our spaces and is willing to do whatever we need to do to accomplish that. The bad is that there is no longer a corridor assisting the isolation along that wall and without an updated plan the contractors building out the room have forged ahead in an ad hoc fashion.

Before I had a chance to review the new plans with the management, the builders framed out the openings on my side the brick wall and placed a layer of sheetrock. In front of the brick they’ve built a new stud wall that runs the entire length of the room, filled it with insulation and sheathed it with a layer of 5/8th sheetrock. The sheetrock is about 10 inches away from the face of the brick.

The openings in the brick wall are still open on the other side. The other studio owner and I were planning on filling it up with insulation before closing it off with a layer sheetrock or 2 on that side. Then we were planning on building another stud wall with 2 layers of 5/8th sheetrock running the length of that room.

I’ve also been spending some time prepping for the addition of my 2 ‘beef’ layers to the bottom of the floor. There are hundreds if not thousands of nails from the hardwood floor above poking through the t&g sub-flooring overhead. I’ve been alternately bashing the nails back flush with the wood or cutting them off with the saws-all. What a pain. However, being up on the scaffold has given me a better view of how close those sprinkler heads are to the joists and it’s 5” rather than the 4” I originally guessed.

Question 1: I realize that what I’m proposing with the walls means that some areas of the wall will have 3 leaves (where the brick is) and some will have 4 leaves (where the openings were). This usually sets off alarms around here but given the amount of mass that the sound will have to travel through and the distance between the outermost leaves, is this going to hurt my isolation? If so what would be the best way to both close the openings and improve the performance of the brick sections of the wall

Question 2: With the extra inch of clearance between the sprinkler heads and the joists it would be possible to forego the RSIC clips and put hat-channel directly on the bottom of the joists, leaving some room to maneuver the 3 layers of sheetrock into place. How much will this affect the isolation from the room above? This is a cost cutting measure on my part. With the way the I-beams divide up the ceiling, I would need in the neighborhood of 85 RSIC clips to hang the ceiling of the live room which at around $5-6 a pop is a fairly significant part of my budget.

[knightfly]

1 - remove the two inner masses, just leaving the bottom(in drawing) and top walls; this will give you about 32" air space between double gyp leaves. Use at least enough insulation to damp the panels themselves, more if you can, and you're looking at a wall tnat nothing else in the building will keep up with. Leave the inner walls, and you'll wish you hadn't.

Two layers of 1/2" wallboard each side of a 32" gap should net you about STC 65, with low end better than 40 dB @ 50 hZ - leave those inner walls in place, and you'll be lucky to get STC 45 with the low end at maybe 25 dB or worse.

2 - leaving off the resilient mounts will cost you (assuming 12" air space) about 12 dB at midrange, and about 3-4 dB on the low end. I'd forego chocolate-covered peanuts for a year to get 3-4 dB better bass iso, without even mentioning the improvement at mids and highs... Steve

[blunderfonics]

OK. Here's where I can't wrap my head around the 3+ leaf problem.



I understand why the 5th example beats the two examples before it because you are increasing the size of the airspace and therefore softening the 'spring' between the masses. So this would seem to indicate that 2 leaves beats three or four leaves.

But look at the 2nd example and the 4th example. Those would seem to indicate that adding the 3rd leaf improves things greatly, but part of this must be attributed to having the outermost leaves decoupled, so maybe that's not the best example.

Take the best example given above and build another wall in front of it and suddenly you go from good to not so good by adding more mass and airspace. This is where I don't get it...



If someone could explain this phenomena or point me to a thread/book/website that does I would appreciate it greatly

[knightfly]

I'm not enough of a mathmatician to fully understand this phenom myself, but I'll give it a shot -

First of all, the STC system is misleading when trying to figure out isolation for MUSIC - STC was developed as a "one number" system for VOICE isolation, and as such it's weighted A LOT toward a center frequency of 500 hZ - therefore it's nearly USELESS for music or machinery isolation, because it doesn't even consider frequencies below 125 hZ. Even that band is not considered as strongly as 500 hZ is when calculating STC.

This is why you can build two very different walls, both with an STC rating of 63 dB, but one will have only around 32 dB TL at 50 hZ and the other might have as much as 40 dB TL @ 50 hZ. One example - double frame wall, 2 layers 5/8 gypsum on the outside of each frame, standard house fiberglass insulation in the cavity - total air gap including frames in one wall = 200mm, the other wall = 400mm - the 200mm wall and the 400mm wall will both test out to around 63 dB STC, but the 400mm wall will have at least 5 dB better TL @ 50 hZ because its m-a-m resonance is around 30 hZ instead of 42 hZ.

Any m-a-m construct will be weakest in isolation at its resonant frequency, and only starts to exhibit serious isolation at around 1.5 octaves or more ABOVE its resonance - so if you were to build two of the 200mm walls and place them 200mm apart, you'd have THREE resonant systems all with the SAME resonance, and that frequency would pass through the walls very easily.

While it's true that the above construction would stop nearly everything in the mid to upper frequency ranges (multi-leaf is NOT bad for mids/highs, only lows) if you were to remove the inner leaves, the m-a-m resonance would drop from 42 hZ to 24 hZ, and LF TL would improve by about 10 dB while the STC would not change at all, even with a 600mm air space between two double layers of 5/8" wallboard. Which wall do you think would stop drums better? Yet with the STC system, both walls would be considered "identical"...

It's also true that the STC of your extra frame/leaf added to the "ideal" of double frame, double outer layers STC 63 example would yield a higher STC rating; but it's the LOWS that suffer with divided air space, and it's the LOWS that are hardest to stop. And stopping lows is done by lowering m-a-m frequency as much as possible, which can only be accomplished by widening the air space and/or increasing the mass. (OK, extra damping helps too; but that's true of BOTH constructions, the 2-leaf AND the 4-leaf.)

I know I've not proven anything here, all I really know is that this WORKS. I've been told by greater minds than mine, and heard it with my own ears. Beyond that, I don't know what to tell you - But if it were MY money, I'd be jerking out those two inner walls and adding whatever materials you save to the two outer leaves instead... Steve

[blunderfonics]

Thanks, that clears things up a bit.

Are there any decent software tools available for calculating m-a-m resonance, TL and/or STC? I think I've seen some screenshots somewhere around here. I'd like to be able to show the guy on the other side of the wall some evidence of what the different wall constructions will do. He's very much from the school of slapping up as many layers as possible with differing thicknesses and densities to achieve isolation.

[Darkhawk]

From your description it sounds like you have more than enough to support the weight, unless your upstairs neighbors decide to float a 4" concrete floor above you

Hey knighfly. There are about five recording studios going into this building and I am part of the crew working on building a second/top floor studio. Blunderfonics and two others are going on the first floor but not underneath my studio.

My question relates to weight and concrete pouring options for the studio floor. How much is not enough (Soundproofing) and how much is too much(structurally sufficient)?

There are S15X42.9 lbf/ft I-beams every 6.5 ft with 2X6's running across them with plywood underlayment and then hardwood floors. I'm not savy enough to have a picture for you yet but I could probably get one to you if it'd help.

Any and all advice would be great! What helps me will help blunderfonics and all those other guys.

Thanks!

[Ro]

Blunder,

Why not ask the landlord to fill up the gap in your brick wall with... bricks.
close that wall and keep mass