John Sayers' Recording Studio Design Forum Archive

I must apologize for the rollercoaster ride people must be going on within this thread. I mean, my plans have changed so much since the beginning, so it is undoubtedly confusing as heck to follow.

They may be changing yet again.

Although I haven't posted much on my thread here lately, I've been busy researching and benefitting by some great minds here and elsewhere. Of particular relevance is Dan Fitzpatrick's "Estimating flanking thru concrete" thread on StudioTips.com.

I'm now considering very seriously not floating my floor, and instead possibly increasing the mass on my walls.

If I increase the number of layers of gypsum wallboard from 3 layers to 5, that is very roughly 11,000 pounds of weight across about 50 linear feet. That's about 220 pounds per linear foot, which I'm quite certain my existing floor can withstand. (If I stand on one leg, I exceed that point weight myself! )

It's not as though I were on a very strong second floor and I were to need good isolation between my room and what is downstairs from that room. The reason floating a floor was recommended to me in the first place was out of concern for flanking across the existing garage floor into the structure (or beyond). How big of a risk is that? If I invest that effort into further beefing up my walls like this, that's more insurance against my walls not becoming the weakest link in the system -- right?

Unfortunately, I do not have the tools required to run the calculations to see how 5 layers of 5/8" gypsum wallboard on each leaf would perform if spaced about a foot apart, and how that number compares to what I can expect out of my existing 4" thick concrete floor. Can someone assist me with this?

If I can pull this off without resorting to floating a floor, I get a lot of square footage back (since I no longer need steps or landings), and I expect to be able to secure a building permit with much less hassle. So, I really hope I can get some "thumbs ups" from the experts here. I do remain open minded though, so if this is a bad idea, given my goals and circumstances, then please be honest and speak up in order to prevent me from making a mistake that I'd be unable to correct.

In addition to the above comments...

Steve, this is from the Mason Industries' FSN Floating Floor Concrete Slab Test Data" thread:

knightfly wrote:Could be you're right; only REAL concern is if your room were going to be sitting on the SAME slab as your neighbor; then, I'd be floatin' fer sure. You WILL get quite a bit of flanking thru your concrete, so your "horizontal" iso won't be super between garage and house unless there's a break in the concrete that completely separates house structure from garage structure . . .

Recall that behind the room is my 10x10 office (which will be empty when I'm rockin' ), to the side of the room is our laundry room (the appliances won't care when I'm rockin'), and in front of the room is our garage (the cars won't care when I'm rockin'). I realize that sound can transmit past these areas, but they'd get the brunt of the assault, right? I would consider replacing the doors to my office and the laundry room with solid core, sealed doors if that would help.

Let me know if you'd like to see a floorplan of the whole house -- I can scan it and drop it in here.

Not necessary; just pointing out that the speed of sound in cured concrete is about 11 times that of air; you want a simple test, have your wife go to different areas of the house while you rap on your garage floor with a hammer. If she can't hear that, find a BIGGER, RUBBER hammer and try again (less high freq, closer to drum characteristics) -

I personally would build your "woodlock walls" first, then if still prob's do an internal floated slab. Mason should be able to tell you if you can get away with your existing slab, and if your slope isn't too bad the adjustable pads could solve that part as well... Steve

Thanks Steve -- great idea. I'll do that.

I'm hoping someone can help me with TL calcs for the following wall constructions:

• Scenario #1A:
  - Stucco
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 12" Air Gap stuffed with Thermafiber or Roxul AFB
  - 5/8" Gypsum Wallboard
  - 5/8" OSB
  - 5/8" Gypsum Wallboard
  
  Scenario #1B:
  - 1/2" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 12" Air Gap stuffed with Thermafiber or Roxul AFB
  - 5/8" Gypsum Wallboard
  - 5/8" OSB
  - 5/8" Gypsum Wallboard
  
  Scenario #2A:
  - Stucco
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 12" Air Gap stuffed with Thermafiber or Roxul AFB
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" OSB
  - 5/8" Gypsum Wallboard
  
  Scenario #2B:
  - 1/2" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 12" Air Gap stuffed with Thermafiber or Roxul AFB
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" OSB
  - 5/8" Gypsum Wallboard
  
  Scenario #3A:
  - Stucco
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 12" Air Gap stuffed with Thermafiber or Roxul AFB
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" OSB
  - 5/8" Gypsum Wallboard
  
  Scenario #3B:
  - 1/2" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 12" Air Gap stuffed with Thermafiber or Roxul AFB
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" Gypsum Wallboard
  - 5/8" OSB
  - 5/8" Gypsum Wallboard

sharward wrote:Of particular relevance is Dan Fitzpatrick's "Estimating flanking thru concrete" thread on StudioTips.com.

I'm now considering very seriously not floating my floor, and instead possibly increasing the mass on my walls.

Hey Keith, speaking of changing one's mind ...

I just made an unexpected discovery that may change my view in favor of floating the floor. It's in the thread you quoted. (June 8 entry)

don't know what this means yet, exactly, just want to keep people up to date.

d

Ah, yes, the "equal loudness scale" thing. I pointed this out back in April in this post, but nobody commented on it.

Sure changes one's perspective, huh?

I found this cool Frequency Weightings Calculator, but I'm not quite sure how to get useful data out of it. I'll bet you do though!

Dan, welcome to my world of flip-flopping!

keith,

that is a cool calculator. someday i will figure out how to use it.

i just found out something cool though. although, i'm exposing myself to ridicule here, i'm sure some other people are in the same boat as me.

it seems you cannot simply add and subtract db values.

for example, 88db + 88db does not equal 176db, it equals 91db. only 3db more.

so naturally you cannot subtract dbs like that either.

see here (some pix missing but still intelligible)

http://www.steve-o.com/public/unc/decibel/index.html

so, i'm a bit confused now, and i feel like the guy who's been walking around with toilet paper stuck to his foot.

now i'm not even sure what TL means

just when you think you're getting it, you realize you know nothing.

dan

http://www.madshrimps.be/gotofaqlink.php?linkid=2307

http://www.mcs.csuhayward.edu/~tebo/Cla ... ption.html

http://www.safetyline.wa.gov.au/institu ... l54_01.asp

http://otto.cmr.fsu.edu/~elec4mus/topics/decibel.html

http://www.cco.caltech.edu/~musiclab/decibel.htm

http://www.electroacoustics.co.uk/artic ... fulldb.htm

http://www.gcaudio.com/resources/howtos/loudness.html

http://www.phys.unsw.edu.au/~jw/hearing.html

http://www.audioholics.com/techtips/roo ... litude.php

http://www.extron.com/company/archive.a ... control_ts

http://www.norsonic.com/web_pages/correlation.html

http://www.norsonic.com/web_pages/measuring_sound.html

http://www.phys.unsw.edu.au/~jw/dB.html

thank you steve!

it's not as if i couldn't find that information ... it's that i didn't know i didn't know ...

hell of course i saw and read that db was logarithmic at some point, i just conveniently forgot it becuase it sounded complicated



back to studyin'

dan

OK. Here we go again. Here's the latest installment of my plan:


CLICK TO ENLARGE IMAGE

• Summary:
  
  • No floated floor
    
    Remove existing garage slab in immediate area of music room
    
    Have new, stronger slab poured to withstand weight of heavy structure
    
    Isolate the slab that the "room with the room" sits on

I think this will solve a number of problems:

• Benefits:
  
  • Eliminates/reduces direct flanking path from inside to outside via floor
    
    Decreases likelihood of slab failure due to overloading
    
    Eliminates many seismic code compliance issues (i.e., no need for "snubbers" -- devices to prevent vertical or horizontal shifting during an earthquake)
    
    Eliminates sloping floor issues
    
    Eliminates "steps up" to floated floor, which would have caused significant loss of square footage to to California Building Code requirements for 36" long landing at bottom of steps
    
    J-bolts inserted into concrete prior to curing ensures code compliant installation of sole plates of all new walls

The "isolated inner pad" may be a little confusing in the rendering. After cutting and removal of all of the highlighted concrete floor space, I'm picturing two separate pours: one being for the area around the front and right side of the room leading to the door connecting to the house (light blue). Wooden forms would be placed along the inside, where the yellow line meets the light blue area. This area would be poured level, flush with the surface at the entrance area, and gradually submerging up to 1 1/4" at the laundry room door.

Then, after that "outer leaf garage area perimeter foundation" has cured, the forms would be removed, some kind of a resilient perimeter "expansion joint" of sorts would be placed along the entire perimeter of the music room (all along the yellow line), and then the "inner leaf slab" would be poured, thicker around the perimeter of course.

Please post your feedback on this approach. Once I know this is the path I should follow, I will attempt to get some quotes for the concrete work.

Keith, this makes the most sense of anything so far; especially since you intend to stay there "until they pat you in the face with a shovel"...

It's definitely "over the top" if you were looking at moving in the next 2-5 years, but VERY sensible under your particular conditions - for one thing, no more GUESSING about how f***ed up your existing slab is Steve

knightfly wrote:. . . especially since you intend to stay there "until they pat you in the face with a shovel"...

I've always joked that my wife and I are planning to live in this house forever, and that after we die, we'll cut holes in our slab and have us buried under the house! So, maybe while the concrete cutter is here, I'll have him pre-cut those plots...

Yes, I'm kidding!

Thanks, Steve. That's Encouraging. Hopefully the price won't scare me off.

Well its about time!! I agree with Steve. Man, isn't that a nice feeling Keith? Decisions like this take all the input you went through to make them. Information is King!!
fitZ

Keith,

This approach makes perfect sense to me.

If you do the demo yourself this is not going to be all that expensive...........

Straight from Means (commercial construction costs data 2004) it would be in the area of $650 including: concrete - rebar - chairs for the bar - forms - in place and finished.

I have to believe you can beat that for residential construction in your area.

Rod

Fabulous! I was mentally prepared for a much higher figure, so this is excellent news.

I don't think I'd want to do the demolition on my own though... Talk about backbreaking! (and I do have a back that gives me problems from time to time...)

I may explore stamping or some other kinds of decorative finishes for the inside slab... It would be nice not having to worry about finishing a floor at the end of all of the construction.

I think my next steps will be:

• Visiting my local building department again to ensure their satisfaction with this approach
  
  Developing a bid sheet that will communicate the most critical aspects of the job and help me compare the bids in apples-to-apples

I'll keep everyone posted!