Exterior wall, width limited. What do you think?

[cadesignr]

The vinyl under the plate was a recommendation on one of the acoustic sites to help isolate the stud. They show it at the top and bottom (yea, I forgot to draw the top). Likely, the building department won't like it and I'll have to change it to foam but I'm willing to give it a try. It's the same vinyl material used on the vertical surfaces.

Hello gents and thanks for the reply Michael. Please forgive ,me for poking my nose into this thread and actually not contributing something, but this is how I learn. By questioning principles, techniques, and materials. I am a designer myself and have learned a lot here simply by sticking my nose in.
As to your use of the vinyl to isolate the plate from the slab. Normal practice dictates the use of a "J" bolt embedded in the slab to hold the wall plate to the slab, but from my understanding, as soon as the nuts are tightened on these bolts...goodby isolation! I'd sure be interested in how you are doing this IF your not fastening the wall to the floor with J bolts. Unless I'm missing something here, which wouldn't be the first time. Hahahaha!
As to the Celotex, that amazes me that it passes code as a shear panel.
Isn't this the lightweight fiberous material with a white primer coat on one face that they used to call "soundboard"? Seems to me that I can break that stuff with my bare hands, let alone a racking building Go figure. They are the experts I guess, and it wouldn't pass code if it hadn't been tested. Personally, if it were in an earthquake zone, I'd be kinda leary though. Are you putting something else OVER this stuff. Seems like it isn't really weather resistant either. I've never heard of it use on an exterior, even under something like vinyl siding or wood siding. Hmmmmmmmm, maybe I AM confused Wouldn't be the first time for that either.
fitZ

[Michael Lee]

their argument for purchasing the Quietrock is that it removes the potential of "short-circuiting" a resilient channel system by nailing/screwing directly through the channel into the studs or other failure modes.

From what I've read, the "short circuit" issue isn't shared by many. I'm certain there are some resilient channel products that are poorly manufactured that may have resulted in failure but I have a difficult problem beleiving that soooo many experts in acoustical sound would recommend the process if it was a complete failure.

We are just trying to get above STC-55 without going much, if any, past 5-3/4". We have a layer of high density vinyl in between the QuietRock and the 1/2" sheetrock. I know it is expensive but I've not found anything with near the properties

Also, if you look around this forum and others, you'll find some good opinions about mass loaded vinyl. I'd recommend shopping around if you decide to use it.

Best of luck[/quote]

Definitely, we will shop the vinyl. There's almost a 100% swing in price on that product from vendor to vendor.

Thanks for the feedback. Once we get close to the STC rating we are looking for, we'll have to shop cost and make certain that project is in budget. After that, it's hard decision time. Right now, we just gotta get in range first and just don't have room for a staggered wall.

Michael Lee
Draftsman

[Michael Lee]

[ As to your use of the vinyl to isolate the plate from the slab. Normal practice dictates the use of a "J" bolt embedded in the slab to hold the wall plate to the slab, but from my understanding, as soon as the nuts are tightened on these bolts...goodby isolation! I'd sure be interested in how you are doing this IF your not fastening the wall to the floor with J bolts. Unless I'm missing something here, which wouldn't be the first time. Hahahaha!

Check out http://www.fabreeka.com/products/washers.htm for products that meet that need.

Michael Lee
Draftsman

[AVare]

So many points to comment on...

Rockwool vs fiberglass:

Check the prices in your region, including multiple manufacturers. Teh prices and difference are all ove th place.

MLV and mass:

What is needed is mass. IT has already been alluded to, but here it is in blunter words. I have never seen any acoustic testing data showing that MLV is better than any other product of similar mass. You have the space, go with gypsum board, HDF etc. You don't have space, go with sheet lead, still cheaper than Quietrock.

Good luck!
Andre

[cadesignr]

Hey Michael, thanks for the link. Interesting. I'm still curious though whether there is indeed decoupling once the nuts are tightened. But, it doesn't need to hashed over any further.
I see you are a draftsman too. I was a detailer for a Store Fixture Manufacturer for close to 20 yrs. Still do it as my own business now. What program are you using in the pics?

fitZ

[Michael Lee]

Sheet leads the one thing I haven't looked into yet. What I did find was that QuietRock is cheaper or as cheap as most 1/8" vinyl products. It's kinda like combining sheetrock with vinyl and getting a hybrid of the two. For our application, it was the best value to date to add lots of denisty in a small space. The QuietRock would be worth it if it would jump up the values in a small space and according to their docs, we might be able to achieve an STC of 57 using three sheets of 5/8" product.

http://www.quietsolution.com/constructi ... tions.html

Check out the detail labeled "Virtual Double Wall - QuietRock on both sides, double layer on one side". I'm figuring the QuietWood is comparable to the QuietRock in STC but have a message into the folks (closed on Sat) to find out.

I appreciate the input about the lead. That had not come up anywhere I've looked.

Michael

[Michael Lee]

What program are you using in the pics?

fitZ

I use MiniCad. It's an older Mac program that does 2D & 3D architecturals but lets me save them in PIC format which I then convert to JPG and edit to a lower rez for repo. It works quite well for what I need it for. I got the MiniCad for like $60 on Ebay and a used PowerMac for $75. Elcheapo Cad setup that would have been state of the art back in 1996 or so. Certainly all I'll ever need.

Michael

[knightfly]

A couple of ways to compare - note that the concrete wall has quite a bit better LF TL - about 6-7 dB @ 50 hZ. The low end is the hardest part on walls, so this is significant.

When you consider that (do a google on Fletcher-Munson) human hearing threshold at 50 hZ is around 55 dB, if you have a TL of 33 @ 50 hZ you should barely hear anything thru the concrete wall until you're generating 85 dB at that frequency.

Also note that these two examples, even though they are within one STC point of each other, will NOT have anywhere near the same isolative properties; the concrete wall will have nearly TWICE the effective sound isolating properties, mainly due to the LF performance. This does, however, assume that nothing else you do will "screw this up" - which isn't likely given some of the constraints you've stated or drawn.

There is no single(commercial) door that will come close to this 55 dB spec that costs less than $4000 - check here

http://www.overly.com/doorCo/Products/index.cfm

for more on that. So you would need to allow for a sound lock and two doors in your plan in order to maintain good iso.

Your ceiling will be another challenge; depth of air space would be your friend here, since you can't hang too much weight on skinny ceiling joists - the increased depth of joists will help both strength and widen the air gap; that way, you could use more layers of gypsum on either side of the ceiling joists AND get a wider gap; both of which will improve isolation.

All the above comments are assuming you're starting from scratch; seems like I read that in earlier posts, correct me if I'm wrong.

Given an 8 x 10 foot section of wall, in my area costs would run roughly $300 for the solid concrete (based on hiring it done - $100 for concrete @ $70/yd, $200 for labor - possibly more including forms, usually concrete contractors re-use these and may charge a portion of the cost to your job) - Materials only for the drywall version would run around $125 for the same 8 x 10 section, if you HIRE it done labor would run about the same; so, if you're NOT DIY it would be maybe a little cheaper for concrete.

A "magic bullet" wall that thick might improve on some aspects, but I don't think you'd get any better LF performance than the solid concrete wall. All these are very expensive. Yes, they give you more mass in less space; but not as much as concrete, and the cost difference isn't insignificant; a single 4x8 sheet of 5/8 wallboard runs around $7, which, if it were MLV, would have about the same isolative properties; the cost of the MLV would run around $1.25 a square foot, or $40 vs. $7 - multiply this by both sides of the wall, and wow...

One thing to consider; which is better, perfectly proportioned space that you can't use because of noise problems, or slightly smaller space that's usable 24/7? If you don't have any more space to expand your envelope OUTWARD, those are your two choices; even tho the "magic Bullets" approach like MLV, Quietrock, etc, may improve TL somewhat in a given wall thickness, I've yet to see any of them that are even close to cost-effective... Steve

[AVare]

A "magic bullet" wall that thick might improve on some aspects, but I don't think you'd get any better LF performance than the solid concrete wall

Total agreement Steve. You summed it up perfectly.

On Quietrock etc walls:

What I did find was that QuietRock is cheaper or as cheap as most 1/8" vinyl products. It's kinda like combining sheetrock with vinyl and getting a hybrid of the two.

I have NEVER seen any test data indicating QueitRock etc is cost effective. Neither for any hybrid type either.

Compare the prices with similar/equivalent systems from IR-761

http://irc.nrc-cnrc.gc.ca/fulltext/ir761/

and compare on thickness, paying attention to LF TL or concrete block walls from BRN-217

http://irc.nrc-cnrc.gc.ca/irc/fulltext/ ... brn217.pdf

and IR-586

http://irc.nrc-cnrc.gc.ca/fulltext/ir586.pdf

Lots of data there, but it should help you significantly in decideing what construction to use.


Have fun!
Andre

[knightfly]

It sounds to me like you're talking about the same Celotex product I'm familiar with; I don't think this is a valid way to build considering the isolation you want and the wall thickness you're limiting yourself to; celotex isn't a high mass product, and having only that on the outer leaf of your wall will weaken the isolation considerably. Using MLV will agravate any moisture problems and help you grow mold -

http://www.buildingscience.com/resource ... part_1.pdf

http://www.buildingscience.com/resource ... part_2.pdf

Here are predictions for two different walls within your parameters; note that the simpler (but NOT DIY-able) concrete one beats the other one by quite a bit -

If you're going to use a mass-air-mass wall, I would use 3/4" OSB on the outside, unfaced insulation, preferably 3-4 PCF mineral wool, and two layers of 5/8 gypsum wallboard on the inside over Resilient Channel - the OSB has more mass than celotex and is stronger against racking - the wall I just described would have an STC of 60-61, with its low end at 25 dB @ 50 hZ, roughly. The concrete is still better... Steve

[Michael Lee]

One thing to consider; which is better, perfectly proportioned space that you can't use because of noise problems, or slightly smaller space that's usable 24/7? If you don't have any more space to expand your envelope OUTWARD, those are your two choices; even tho the "magic Bullets" approach like MLV, Quietrock, etc, may improve TL somewhat in a given wall thickness, I've yet to see any of them that are even close to cost-effective... Steve

Thanks Steve.

That I guess sums it up. We either have to scale down the room a little bit or make it larger but where it is we are going to pay through the nose to achieve the level of isolation we are looking for. I started with the staggered wall with double 5/8" but ran of our room quickly.

I greatly appreciate your comments and your insight.

Michael Lee
Draftsman

[Michael Lee]

I have NEVER seen any test data indicating QueitRock etc is cost effective. Neither for any hybrid type either.

I'm not married to the Quietrock idea it's just they they have an exterior sheathing that paired with their interior product they claim they can get to STC-54 with it. I'm just starting to look into it and have no claim to expertise. Just with the limitations, it was worth the review.

The only reason it might be cost effective is from a labor standpoint. I think the cost of materials is more but you only apply one layer to each side vs the exterior and RC, Rock, Viny, Rock layer on the inside to get close the the same STC they are claiming.

Again, I'll be doing a lot more research on their product before this is over. I'll want to see some independent information to support their positions.

Thank you for all the great links. The 4" concrete has its advantages but I'm not certain if that's the direction the owner wishes to go.

Michael Lee
Draftsman

[knightfly]

From what I can see, the 5-1/2" concrete wall will do as good or better than using two layers of "quiet rock" product, and at approximately HALF the cost - that's why I brought it up... Steve

[Michael Lee]

celotex isn't a high mass product, and having only that on the outer leaf of your wall will weaken the isolation considerably. Using MLV will agravate any moisture problems and help you grow mold

-

I know about the Celotex but when I started the project, we had an exterior and an interior wall. Due to size contraints, I only had 1/2" left for exterior sheathing and 1/2" OSB wasn't very good either. At least the Celotex breathes a little. I agree about the vinyl, hugh moisture trap. If we were to use that product, one side of the structure had to breath if the other side couldn't. Just my reasoning.

If you're going to use a mass-air-mass wall, I would use 3/4" OSB on the outside, unfaced insulation, preferably 3-4 PCF mineral wool, and two layers of 5/8 gypsum wallboard on the inside over Resilient Channel - the OSB has more mass than celotex and is stronger against racking - the wall I just described would have an STC of 60-61, with its low end at 25 dB @ 50 hZ, roughly. The concrete is still better... Steve

I was thinking of 3.5" of Owens Corning CB-300 insul if that's okay. Let me know if the mineral wool is better and what products you prefer (brand wise).

Thanks again for your time and expertise. Did not want to proceed with construction drawings until we had worked out all these details. Your guidance is appreciated.

Michael Lee
Drafsman

[Michael Lee]

From what I can see, the 5-1/2" concrete wall will do as good or better than using two layers of "quiet rock" product, and at approximately HALF the cost - that's why I brought it up... Steve

I appreciate the advice. I will definitely consider it if we cannot make the walls any larger. LOVE that program. Seems quite unique.... Michael Lee - Draftsman