John Sayers' Recording Studio Design Forum Archive

Posted: **Sun Aug 08, 2004 1:58 am**

I've got a neighbor on the other side of my shared concrete wall.

Would floating risers for drums/amps and properly constructed walls do the trick?

Posted: **Sun Aug 08, 2004 2:36 am**

Kind of a sparse question, but generally yes - here is a document from our Canadian neighbors that may help explain - granted, this was a study of wood construction, but the physics still apply - read the paragraph under "results" for a general idea.

http://www.cmhc-schl.gc.ca/publications ... /96228.htm

If you're planning to have acoustic drums, nothing less than a total floated room-in-room will keep your neighbors from wanting you dead - but before you try something that involved, you need to find out a LOT more about your existing construction, and preferably get a local structural engineer involved - the stresses generated by point source loading caused by floating an entire room can be tremendous, so you REALLY need to know what/how/when, etc -

If that's the direction you want to go, I can help point you in the right direction... Steve

Posted: **Sun Aug 08, 2004 3:55 am**

I thought that if you were in a basement, and the floor is a concrete slab over earth/dirt, then a wooden floating floor is more contraversial. i.e. the dangers of building a floor that amplifies the sound are about the same as the likelyhood of building one that makes it quieter (at least in the sub 50hz range).

The internet says a kick drum is 60hz, and a bass drum is 32 hz.

Posted: **Sun Aug 08, 2004 5:42 am**

Bob:

It is the same as most things in acoustics; if you don't know what you are doing, you can mess it up big time. In this case, understanding MAM resonances. That of course course the acoustical aspect. Steve mentioned several others.

Posted: **Sun Aug 08, 2004 6:16 am**

the building is a 2 story carraige house approx. 20'x50', the control room will be roughly 14'x14' and the live room will be roughly 15'x17'.

walls are concrete block. the subfloor will be poured concrete over dirt/old concrete.

I'm beginning to see the big picture, however, I'm starting to realize how crucial the stress points are. Am I correct in saying that there is no absolutely perfect material out there for floating?

knightfly wrote: One thing few cover on floating floors - rubber is a spring. Springs ONLY act like springs when they are NOT at the ends of their travel. When they ARE at the ends of their travel, they are NOT resilient at all, and could just as easily be THROWN AWAY.

The only way I know of to be sure of the total amount of cross-sectional area of rubber you will need for your particular project (unless you're more of a mathmatician than I am) is to experiment - you want the total weight of ALL the floated stuff to cause the rubber to compress by at LEAST 15%, possibly 20 - this includes EVERYTHING that will be supported by the rubber - floor, walls if they're floated on the floor, ceiling if it's supported by the floated walls, console, drums, EVERYTHING that is pressing down on that rubber must be figured in.

Find weight figures for all your building supplies, do a material list to find out how many of each product, do the math, and get a close estimate of what everything weighs. Include musical instruments like pianos, organs, mainly heavy items - and anything that's permanent, like console, speakers, glass, doors, framing, etc -

Once you find out what your total "sprung weight" will be, it's time to experiment. The way I would (will) go about this is to start with a very solid work bench - take a piece of your floor framing, oriented the way it will be installed (flat or on edge) and fasten a couple of pieces of lighter wood to the ends so that the framing piece is the center of a "U" - this will stabilize the piece so it won't fall over. If you're laying framing flat, don't bother with this step.

cut a small sample of your rubber, no more than 1" wide, and at least 1/2" longer on each end than your frame width. Lay the frame sample on the rubber, all resting at the edge of your sturdy workbench. You will need access to measure some things later.

Get a full set of encyclopedias, or some workout weights, something with a lot of mass - First, firmly push down on the framing sample so that you take any "slop" out of the interface between workbench, rubber and frame. Measure VERY accurately the distance between the framing sample and the top of the workbench, as close to the rubber as you can get. This is your "zero reference" - this is the thickness of the rubber WITHOUT compression.

Next, start stacking weights on top of the framing member, directly over the rubber, til you compress by about 20% - make sure the rubber is not constrained horizontally in any way, or the measurement isn't valid. In the case of 1/2" rubber, you would need to add weight til it was only .4 inches thick (measured between your framing sample and the top of the workbench) - Weigh the total material you stacked up to accomplish this, divide by the total area (in sq. in.) of contact BETWEEN RUBBER AND FRAME ONLY, and you have the weight per square inch that's necessary to accomplish 20% compression.

Divide your total estimated "sprung weight" by your "weight per square inch" figure above, and you have the total area of rubber to be distributed beneath your frame.

Allow for a few extra pucks under areas where heavy things will be - if you're using a serious console, put a few extras under where the legs will sit - same in areas where a piano will be. Allow for twice as many pucks around the perimeter and under any other walls. Don't add extra pucks, steal them from less rigorous areas and re-adjust the spacing.

You will probably find that laying frames flat will require too long a space between pucks for proper compression - If you need less floor height you can narrow the rubber pieces some, but watch getting too long a span between supports especially for flat laid frames.

I know this sounds like a hell of a lot of work, and it is - still, NOT doing this is kind of a Crap Shoot; you may get lucky, or more likely you'll be back wanting an easy fix for having taken the easy way out. There isn't one. Just because you're not a physics major (neither am I) doesn't mean you can ignore the laws of physics and get away with it - if you don't believe that, jump off a 10-story building while swearing you don't believe in Gravity... Steve

Is there anything out of the ordinary I need to take into account when we pour?

thanks!

Tom

Posted: **Tue Aug 10, 2004 3:13 pm**

So the studio goes on the first (ground) floor? Will you float a floor on top of that, or will it be the final floor?

Square rooms are horrible for acoustics, is there any way you can change one dimension of the CR by about a foot? You'll thank me in the long run -

Floating wood floors - EPDM rubber, 60 Duro. Slightly overstuff with rockwool or rigid fiberglass, you don't want the floor to ring. Floating concrete floors - go to kineticsnoise.com

http://www.kineticsnoise.com/arch/index.html

but bring your wallet... they don't sell direct if i remember correctly, they'll have a rep contact you if you're interested. Check out the RIM system, there are pdf's that show more on installations.

Walls - filled, or hollow? What are your intentions for isolation, finish, acoustics, etc?

Seems like you're rushing into this; I hope you've been lurking for about a year or you may get ahead of yourself (never a good idea with the cost of building materials rising daily)

Let us know, plus maybe a drawing of what you plan to do??!? Steve

Posted: **Wed Aug 11, 2004 8:33 am**

I've been doing casual research for about a year and a half now, much more in-depth in the last couple of weeks or so; I guess my questions look dumber from the other side...

As far as the orig. question is concerned, I was just second guessing myself. Some others in this forum said they had good results w/o floating, so I thought I'd entertain the idea. That said, it's looking like I'm not gonna risk it.

I've worked out a few designs (not square ones...

) using some of John's concepts as well as the SAE ones. Currently, I'm thinking of floating 2x6s on 16 or 12" centers w/ u-boats on top of the concrete. The floor will not touch the steel columns, unless someone can convince me that I can have them running through my floor/ceiling w/out any kind of loss of isolation. As far as the minimal space that could be gained; I don't think it's worth taking the risk. The floor decking will be particle board, 5/8 sheetrock, w/ ply on top. Perhaps hardwood on top o that? maybe I'll just stain the top layer of plywood (a'la the new Right Track studio in NYC).

Walls/ceiling will be framed directly to the floated floor on top of either SheetBlok or cheaper alternative w/ 2 or 3 layers different thicknesses of sheetrock, filled w/ rockwool...

1 question I have is:

Should I attach another layer of rockwool (or other insul) to the structural concrete wall? If so, how?

I don't need to worry about lack of air because I'll have plenty (see steel columns and old concrete columns on far right of pic).

thanks for your time!

T

p.s. my donation never got picked up last week...

Posted: **Thu Aug 12, 2004 6:59 am**

On the extra insulation - never hurts to have more insulation in a wall. As to fastening, is this an interior wall or exterior? (What's on the other side, the great outdoors or another room)

Generally, vapor barriers go toward the living side of the wall, except in the deep south where most of the year the space gets cooled instead of heated... Steve

Posted: **Sat Aug 14, 2004 12:54 am**

I'm talking about insulating the interior structural (concrete) wall. There are garages on both sides of me.

Posted: **Sat Aug 14, 2004 8:45 am**

Can't be sure by the pix, and you forgot to answer the question about whether this stuctural concrete wall is hollow block or solid concrete - from the pic, it looks to be solid but could also be blocks that have been "rendered" with a mortar spread.

Here's how you fasten acoustical products (fiberglas, rockwool) to concrete -

http://www.acousticalsolutions.com/prod ... _clips.asp

If your walls are solid concrete, you can use a construction adhesive designed for concrete and glue the clips to the concrete, then just "impale" the insulation batts on the clips - it doesn't hurt to use some adhesive on the wall near the clips just before impaling the insulation.

I'm not a fan of using particle board as a bottom layer of floors that are over concrete - moisture and particle board aren't a good combination - also, if you're going to float the entire room on top of this floor, I'm not sure if using a sandwich of gypsum in the floor is a good idea either - I've not done this, and I'm a bit leary of that much weight pressing down on a particle board and gypsum floor without compression problems.

Personally, given your set of conditions I would opt for Auralex U-boats (they are EPDM rubber, because it has about 2.5 times the useful life of neoprene) - I would calculate the rough weight of the entire room (see my posts on this page for an idea of this)

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=839

Even for 100 PSF live load, 2x6's on 24" centers can span 5'7", so you have a fairly wide range of puck spacing you can choose from - this needs to be based on a reasonable amount of compression per puck, rather than "carpenter logic" (using 16" or 24" centers just because it's customary)

I would use OSB for the bottom floor panel, then particle board or MDF, then plywood - use rockwool or rigid 3 PCF between joists, and if it doesn't stick up above the joists by about 1/4" add strips of loose fiberglass between the joists - you want a little compression of the material so it damps the floor panels between each joist or you'll get LF ringing.

This construction will give a more solid base for resting walls and ceiling weight on the floated floor -

Walls - Impaling clips glued to the concrete, insulation on impaling clips, then inner frames on floated floor, (with pucks spaced to approximate about 15-20% compression) - 2.5 to 3 PCF insulation batts between studs, then if you want dissimilar weight panels I would sandwich 5/8, 3/8, 5/8 gypsum on one side of the studs ONLY - if your situation is controlled enough, you may want to use firecode gypsum for the innermost layer - this would give you three different material properties for best coincidence performance, and enough mass for really quiet walls. In order to keep the insulation batts pressing lightly against the wall board, you can use strips of wood or steel stud fastened to the INSIDE of the frame horizontally to keep the insulation from trying to fall out the back - to keep it from sagging (depending on what insulation you use this may not be a problem) you could screw impaling clips to these cross pieces before insulating the frame. You want the insulation to touch the wall panels for damping.

Ceiling - if using steel studs, you need the heavier "structural" grade to support the ceiling if using steel framing. For wood, just 2x4's are fine - 24" centers makes it easier to insulate.

If you use 16" centers for ceiling joists, you can span 16' or so with 2x8's - if you use 24" centers, it needs 2x10's.

Can you describe the existing ceiling construction? the pic looks like wood framing with some kind of sheathing over. Please be specific on all materials, spacing, sizes of boards, etc - I'm concerned about m-a-m resonance here, as well as ceiling damping.

Also, what's the moisture/floor/drainage situation there? Check out the basement PDF linked on my first post on the floating floor thread above if you haven't already -

I know this is a lot to digest; I'm just not a big fan of "DIO" (Do It Over), and it only takes one small oversight to screw up a project like this... Steve

Posted: **Mon Aug 16, 2004 11:38 pm**

Thanks Steve, that was really helpful.

I'll definitely bail on the particle/sheetrock/ply floor sandwich and go with your's.

To answer your q's:

The concrete is in fact, hollow block. I also forgot to mention that a portion of it is brick as well. Come to think of it, where the studio lies, the majority is brick.

The ceiling is made up of 2x10s on 16" centers, no sheathing. 2nd floor subfloor is plywood nailed and glued at the seams. The steel beams are another issue, I suppose.

The garage will remain and drainage will be a grate that runs along the inside of the garage door. The poured concrete floor will gradually slope down to ground level at the garage.

Posted: **Tue Aug 17, 2004 2:41 am**

Just to help tie this thread to your pending design, I'll do a "Vulcan Html Meld";

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2081

Have you reached a decision on which plan you'll be using?

If most of your walls around the studio are brick, you should definitely get a mason to render them about 1/2" thick before doing anything else - rendering both sides of standard brick walls improves STC by about 6 dB, so a thicker coat on one side should help by at least 4.

Where there are hollow blocks, you should do two coats of heavy paint; gives close to the same STC (around 45-48 dB) - then, impale insulation, add inner frames, and double sheet rock with more insulation - the next links show one method of keeping insulation in place for the inner wall -

http://www.johnlsayers.com/phpBB2/viewt ... &start=120

http://www.johnlsayers.com/phpBB2/viewt ... &start=225

Pix posted on 6/21 on the second link show how Aaron used hat channel on the inside of some walls to keep insulation from pushing out, and to maintain light insulation contact with wallboard for damping.

Ceilings - do you have enough headroom to suspend new ceiling joists UNDER the steel beams (and hung from them)? if so, the upper floor sheath and your new ceiling layers (all in one leaf) should make an excellent mass-air-mass barrier. Another possiblilty would be to do your second leaf off Resilient Channel hung on the existing joists, then do a sloped false ceiling UNDER the steel beams and fill with bass hangers. That would probably be the way I'd go from what I can see so far.

Hope that helps... Steve

Posted: **Tue Aug 17, 2004 4:28 am**

I'm leaning back to a variation of that 1st design, mainly for the easy access between the 2 rooms. I do have another, based on John's that I like as well, but it involves going through the iso booth to get into the live room. I've given up on the computer drawing for now; back to protractors and graph paper for me! I'll get an update on the 'puter soon when I get this thing figured out.

I'm not sure I'm following what you were saying about suspending the ceiling. Do you mean physically hang it from the steel beams in order to take weight off of the walls? If you were to get involved with existing joists, etc, wouldn't that compromise isolation?
The plan so far, was to frame on top of the walls to keep the 'room within a room' thing consistent. I'll need some space to let ductwork, etc get under the steel beams; so that'll be plenty of air. I've got about 10'6" from the new concrete floor to the bottom of the steel, which is great for now, but will quickly get eaten up by all of this framing and duct work.

Posted: **Tue Aug 17, 2004 10:30 am**

I had an idea how you could get your isolation totally above the beams, then hang a sloped false ceiling and make the area above it into bass trapping, but the steel beams (flanking noise) and ductwork got in the way - looks like your method makes the most sense for this... Steve

Posted: **Fri Aug 27, 2004 7:21 am**

I forgot, but the original plans call for the concrete walls to be framed and rocked too (before I build any studio walls, ie: the room within a room) .
I definitely need this in the office (far end of building opposite the garage door) for insulation, etc.

Should I have them stop short of where the studio will be? It seems like a lot of $$$ spent for not much more 'true isolation'.....

a link to my 'old' drawing for a reference pt....

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2081

they're framing now! I need to make a decision on this!

ahh the stresssssssssssssssss

John Sayers' Recording Studio Design Forum Archive

is floating floor a must......?

is floating floor a must......?