John Sayers' Recording Studio Design Forum Archive

This is My first post, Great site. I've read the FAQs, lots of great info useful info.

Over at the AVS forum everyone is raving over the use of RSIC clips instead of resilient channel (better decoupling, especially low frequencies) and this GREEN GLUE( http://www.audioalloy.com/green_glue.htm ) in betwwen 2 sheets of 5/8" drywall. Green Glue is supposedly the cats meow for Dampening and supposedly lowers TL frequencies into the low 20hz range. Any thoughts on this?

A little background on me: I'm a construction project manager and I've been in the trade 25 years plus (born in the business,father was a contractor), I also have a degree in mechanical engineering. So the technical and building aspects of this project are well within my grasp.

Me and My band members are planning a sound studio in our guitarists basement. The space is approximately 23'x15'. Heres what we got, 10" of concrete on 2 sides, a 3" airspace, and then 2x4 walls framed floor to ceiling. One side has 2x4 exterior walls, 6" airspace between and another 2x4 wall. Both walls have 31/2" batting. The last wall is 2x4 with 31/2" batting and5/8 drywall, this wall goes to a garage space attached to our studio space.

Setting the stage:
Band has two full drum kits and a bass player that likes bottom end. All the frequencies are important but our primary concern is keeping Low frequencies in and flanking.

Right now theres paneling on the walls which is getting ripped out, and 31/2" fiberglass bat insulation. The ceiling is cross firred with furring strips and covered with 12"x12" accoustic tile and 31/2" fibrglass bat insulation.

Directly above the studio space is a living room with a heavy carpet and pad, and a kitchen with ceramic tile flooring.

I realize most of whats there is almost useles except for the fact that the 2x4 walls have nice airspace between them and the bats might be usefull. The acoustic ceiling may offer some sound benefits once it's covered with 2 layers of 5/8" drywall.

Here's the begiinnings of what I want to do:
*Install more batting in airspaces.
*Decouple walls to floor and walls to ceiling with some sort of padding between bottom plate and concrete floor , ceiling with transverse resilient channel, Maybe? OR some sort of homegrown decoupling device as shown in th FAqs
*Install RSIC with hat channel on all walls and ceiling followed by 2x5/8" drywall with either Green Glue in Between or MLV glued in between with vinyl adhesive( auralex site reccomendations). The MLV offers more mass and some damping, The GG offers more damping but very little Mass. Another consideration might be 5/8,GG, MLV, 5/8. Which do you think is better and how much better?

Is it worth the extra cash to use the MLV in conjunction with GG?
The concrete floor is attached to the concrete walls, poured in place, Should we detach the floor from the walls by cutting a saw blades width , full depth,around the perimeter of the room? Fill the sawblade track with or silicone or GG? Is it worth the trouble? Or will decoupling platforms under the drums and speakers be a better/cheaper solution?


Sorry for the long post. If you have additional Questions, by all means, shoot!
Thanks in advance.

Marcel

Marcel, welcome; good start, but you've missed a few of the highlighted areas here -

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=3231

I'm assuming from your comments that you've read about 2-leaf construction being the most efficient, but you missed the part in the above link about acoustics being THREE-dimensional, or I've missed your ceiling height measurement...

Also it would help to know the joist depth/spacing/spans so we can get an idea of capacity for additional layers there.

As to Green Glue and MLV, I agree with Rod Gervais (Mr. Construction hisself) that these mainly raise costs - I don't disagree that each works as advertised, and I'm familiar with the concepts of each; but here's MY take -

GG costs about 80 cents per square foot applied; that's $25.60 per 4 x 8 "sheet" of material, which would buy about 3.5 sheets of 5/8 drywall in my area. So for the same money, instead of two layers of drywall you could have FIVE - for TL, especially LOW frequency TL, MASS IS KING, as is the air gap between two masses.

MLV - cost per "4x8 sheet" runs about $32, IIRC - yet the mass value is worth about $5, in terms of equivalent drywall cost...

Where the GG might prove useful is in ceiling construction, where space and weight limitations might apply (low basement, marginal span joists, high isolation needs) - for this, I would think that two layers of 5/8 with GG between, supported on RISC's/channel and completely filled with insulation, would be a good way to go.

Keep in mind that if you could afford the weight/thickness of a third layer, it would (I think) give better isolation at low end than using GG and only TWO layers. Again, insulation; this damps the panels (not as well as GG, but no one's ever complained about wall/ceiling ringing)

If you can fill in the blanks (use the "before posting" page as a guideline) I can do more; also, I'm hoping that by "Right now theres paneling on the walls which is getting ripped out", you mean ALL paneling other than the concrete (or outer sheath) -

Generally, when trying to re-do a space for best isolation as you are, my preferred method is to start by gutting everything that isn't necessary to hold up the building (EXCEPT the outer sheath, usually), then doing a thorough analysis of that outer shell and figuring out how to make the ENTIRE outer shell into a high mass "first leaf" - this includes ceiling and floor as well as walls.

Then, allowing for as much air gap as can be spared (12-15 inches is NOT excessive for good low end iso) build the INNER leaf as heavy and tight as possible, with as little mechanical connection to the outer leaf as you can. Sway braces, wall bedding, separate frames, etc, all go toward improving isolation as does insulation. (Air gap is NOT considered as the distance between FRAMES, but the distance between the innermost layer of paneling on the OUTER leaf and the FIRST surface of the INNER leaf that the sound encounters on its way INTO the space.

Example - double framed wall, 2x4 frames, frames are 2" apart - drywall on the outside of the outer frame, inside of the inner frame - the "air" gap, even though filled with insulation, would be 9 inches. (2x 3.5" for the frames, + 2" for the space BETWEEN the frames)

I mentioned that because some people get confused into thinking that a "12" air gap" means having 12" between the frames.

Gotta move on for now; please re-read the "first post" link and fill in any blanks, remind me of anything I missed (I'm sure I did ) and we'll go from there... Steve

Thanks for the reply. Heres a very rough Basic layout of the room. The bottom of the ceiling joists are about 7'2" off the concrete floor. So there s not a lot of headroom. The concrete wall on the left is buried under dirt, the concrete wall on the bottom of the drawing is completely buried at one end and te grade tapers down towards the right and then the concrete steps down to floor level. The right wall is 2x4 innere and 2x4 outer. Distance from exterior sheathing to the inner leaf would be approx 16". I thought that was pretty good. On the concrete walls the distance from the inner part of the 10" foundation to the inner drywall leaf will be about 7". The wall at the top of the drawing is only a single 2x4 wall which leads to a basement Garage, Theres no room to add an inner wall there, so I'm hoping to be able to add the 2 layers of drywall with rsic clips and green glue. As you can see all the walls are parrallel. I wish there was more space so that we could design a room with no parrallel walls but we need as much space as we can get. I was hoping to kill the room modes with foam or fabric encased wool bats, placed here and there. Our main objective is to have a guiet practice studio so the nieghbors don't freak out, and so the other residents can watch TV above while we're playing in the basement. We're planning on putting double doors on all the doorways leading out of the practice space. The round thing in the bottom left corner is a water heater that we might move into the garage.

The ceiling joists are 2x10". the left wall in the dwg goes to the outside. The niehbors are close, like 25' away on either side of the house. If this isn't doable, let me know, because nothing's been done yet.

BTW: The budget for this room is approx $5000. This is for framing. extra doors, Drywall, Caulk, channel and labor to hang the drywall and anything we'll need to tune the room once it's soundproofed. The actual hanging of the drywall and taping will be subbed out since it's hard heavy work and we're soft old guys.LOL. All the Caulking and chanel work and carpentry will be handled by be and the band members.

Marcel

You may have noticed that I removed the extra dead space to the right and bottom of your drawing; that's what this part of the "before you post" announcement is for -

Please resize as necessary to keep graphics UNDER 800 pixels, preferably under 750, wide; otherwise it forces people to scroll sideways to read every line of text.

Next, are your 2x10's running the long way or the short way, and do you know the exact makeup of the above floor layers?

Beyond those, looks fairly doable other than the typical low ceiling thing; if your joist spans/weights allow, at least 2 layers of 5/8 rock on RC or RSIC's (better) with complete insulation fill (no backing on insulation) will be about the best you can do. Hopefully no one in your band is over 6 feet; under the wallboard you will still want at least 2" rockwool with a couple inches spacing away from the ceiling, this gets you down to 6'8" headroom

Make sure your "rocker" knows this isn't your average rock job; no little "fudged" patches, no "just making it LOOK good", you need SOLID double layer gypsum EVERYWHERE, and full ACOUSTIC rated caulk. Have him read the REFERENCE section through, at least the "complete section" first few posts, so he at least STARTS to understand the physics of isolation.

Fill in the few remaining blanks, plus anything else you may think of, like any intruding pipes or ducts, etc, and we're on our way.

BTW, just ran rough costing for materials - not sure of pricing in your area, or what hat channel has done in the last 2 years, but based on $8 a sheet for 5/8 4x8 drywall and $1 a foot for channel and $5 apiece for RSIC's, materials are looking right at $2500 - this includes rock, screws, mud, tape, INNER insulation (std. UN-faced fiberglass fill) RSIC's, hat channel, $3-400 for framing, NO doors or windows, NO paint, NO acoustic treatment inside, and NO labor.

If your area has better prices (sheet rock isn't that high on my side of the continent) then maybe a bit less, but it'll get eaten up by SOMETHING that wasn't considered

Still, definitely not as ridiculous as living in a rented third floor apartment next to two crotchety old ladies and wanting to play drums at 2 am for total cost of $100, with "no permanent construction"... Steve

Steve; Again many thanks for your reply. I'm gonna try to detail this sketch a little more showing where the exterior concrete walls are etc...

You can see where the carrying beam is and the direction of the joists. The stairway and garage seperating wall is gonna be the trickiest, I think because of the closet door below the stairway. Incidentally there will also be a door at the top of the stairs. I'm hoping that the stairway will act as a sort of airlock. The whloe underside of the stairs will be treated like the ceiling. Because of that stupid closet door beneath the stairs it complicates the crap out of where to break off the sound barrier. I could really use a little help there. I suppose, once I dig into this thing a little, some things will become more apparent. I've also decided to move the water heater into the garage area to give us more room and also to eliminate the closet nightmare.

Another note, all the electrical and lighting will be surface mounted and wires will be caulked as they go thru the drywall.

Does it matter weather we use glass or mineral fiber in the wall and ceiling cavities? Or should we use a little of both for different densities.

What is the purpose of installing mineral wool beneath the ceiling drywall? Is it for accoustics inside the room, or for soundproofing?or alittle of both?

Marcel

Heres another pic done in sketchUp. Posted in SketchUp format. There's quite a few details missing but you'll get a better idea of the space.

Insulation INSIDE the walls/ceiling should be no more than 3 pcf, 2.5 seems to be about optimum; heavier tends to cause a partial "three leaf effect" of worsening bass TL and improving mids, which we don't really care about since bass is the hardest to control. Even standard house insulation, if there is NO BACKING on it, can be used here with complete fill and you'd only lose maybe a couple dB of TL compared to the rockwool or rigid fiberglass.

Insulation OUTSIDE the walls is ONLY for acoustic purposes; here, 3pcf is about minimum for decent results in reasonable amounts of space.

The ceiling "cloud" is to "make the ceiling disappear acoustically" - 2" won't completely do that, even with a 2" air gap; but unless there's seven of you and you're all really good friends with Snow White, it's the best compromise... Steve

For all you guys that don't have sketchup, heres a pic of the room that shows the concrete walls with the studded walls built inside.

Another concern of mine is the carrying beam and the 2- cement filled steel encased columns that support the carrying beam (not shown). How should those be treated?

Wrap 'em with 2-3" of rockwool and cover with cloth, velvet paintings, old used fur coats, silk-screened concert T-shirts, etc - they'll disappear acoustically for all but really low frequencies, which'll just "wrap around" them anyway... Steve

On the ceiling treatment: Can suspended ceiling track be used to space the 703 panels down from the ceiling? ie: hang bottom of track down 4" and then install 2"x2x4 703 panels in the track, much like a traditional suspended ceiling.

Will the track introduce a problem?

The only thought I had is that the track might resonate at some frequency. Maybe I could caulk all the track joints with glue or accoustic caulk to prevent resonance and hang the track with rubber strips instead of traditional wire.

Or is that a completely dumb idea?

Marcel

Don't see why that wouldn't work; just having the 703 panels in contact with the grid should totally damp any resonances from the metal. Only other thing might be some higher frequency specular reflections off the grid; maybe add some heavier cloth over (like burlap) which would kill most (if not all) HF reflections from the channels... Steve

Steve, thanks for the reply.

What the hell is a "specular reflection"? Is that the same as a reflection you'd get off a bare drywall wall?

I suppose there'd be no harm in putting up the track with the 2"-703, and if the reflections become a problem, I could just cover the track with burlap.

Marcel

Sorry;

spec·u·lar (spµk“y…-l…r) adj. Of, resembling, or produced by a mirror or speculum.

IOW, point source reflections - mostly high frequency related... Steve

Steve thanks again for your reply:

We'll be doing some demo in the basement space in a couple of weeks, at which time I'll be posting some pics of the overall room and also some areas that I feel might be problematic such as the stairway.

Half of the floor above is 1/2" plywood with 5/8" particle board(like the stuff they make formica tops with similar in density to MDF) on top, then carpet pad and thick carpet. The other half is 1/2"plywood-3/4" plywood-5/8" ceramic tile.

I can't wait to dig into this thing with pictures, so I can get more specific answers.

After reading about some similar spaces (Fitzpatricks), I don't think I'm gonna float the floor, since the concrete for the outer leaf and floor are mostly under ground, which should provide some decent damping (I hope ). This too will be reconsidered once I can get some pictures up.

Marcel