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Roxul sound proofing opinion

post #1 of 100
Thread Starter 
I'm currently finishing a basement in my house, and am planning on putting Roxul Safe'n'Sound insulation in the ceiling between the joists, to stop the transmission of sound up into the mail floor of the house.
The house is older, and the joists are 2x6,s (16" on center) and I am debating on whether to put in one layer of the Roxul stuff or two. The Safe'n'Sound stuff is only 3" thick, so I can physically fit. It's just a question of the effectiveness of $200 worth (second layer) of Roxul will make a huge difference or not.

The final ceiling will be suspended ceiling tiles.

Any thoughts on this? Will a second layer of this stuff make a huge difference?
post #2 of 100
There's been a lot of threads on insulation recently. I believe the experts will chime in and tell you to save your money and go with regualr pink insulation rather than the Safe'n'Sound. For less money, you could just fill the joists with R-19 and be good to go.
post #3 of 100
Either way you go, fill the cavity. The denser mineral wool will help a little but it's considerably more costly. If you really want to help, use cheaper insulation and put up another layer of drywall and Green Glue.

Bryan
post #4 of 100
Thread Starter 
I'm not drywalling the ceiling. Suspended tiles is what I'm doing.
post #5 of 100
I insulated my HT with Roxul Insulation (normal stuff for the wall...greenish)

When using nail guns you could not hear them through the walls or through the ceiling....you could only hear the sound coming through/under the door.

I also had double drywall seperated by sound bar. I am very glad I used the Roxul...infact I used it throughout my entire house, except the attic. I would highly recommend it.
post #6 of 100
If you're doing a drop ceiling, then you'll not have much in the way of isolation anyway. It simply won't stop bass from getting out. Just use the fluffy stuff and at least get some broadband bass control inside the room out of it.

Bryan
post #7 of 100
Quote:


Either way you go, fill the cavity.

I thought I was seeing in some of the other recent threads that anything beyond R19 was diminishing returns. I guess I'm little confused. R19 would fill a 2X6. Are you saying now to even fill a 2x8 or 2X10 cavity? I tought that little bit of air space OK.

Tom
post #8 of 100
Thread Starter 
I found this:
http://www.greengluecompany.com/pdf/...oorDiagram.pdf

How much effect does adding drywall between joists make? If any?
post #9 of 100
You would be adding mass which is what you want. This seems to be extremely labor intensive, why not just hang the drywall off your joists instead of drywalling between them?
post #10 of 100
The more you can fill the cavity, the better off you are. It's cheap enough to add a layer of R13 to a layer of R19 in the grand scheme of things.

Drywall added to the bottom of the floor above will add mass and help transmission slightly

Bryan
post #11 of 100
Thread Starter 
Thanks Bryan.
I think the most I can stuff between the 2x6 joists is some Roxul R22 insulation.

I'll stuff as much insulation as I can, and see what that gets me in the end.
post #12 of 100
I believe Safe n Sound is 3" in order to keep 1 " of air space (in a 2x4 wall) for further soundproofing. Doubling the insulation in a 2x6 wall would obviously take away the airspace that the product was designed to have.

If the choice is 1 layer of Safe n Sound OR 2 layers, I would go for 1. But some of the above suggestions may be better still.
post #13 of 100
Hi Outsider,

I spoke to a tech at Roxul (in Milton) - number on the web or on the S&S packaging... He said that the mineral wool should be a bit better for bass control because it's denser than the pink stuff.

He said using more than 1 layer in ceiling joists is overkill. It works negligibly better than 1 layer, better to use the money in other ways to soundproof.

I used 1 layer of S&S in most of my ceiling joists, except for the ones with ducts or pipes running through. For the joists with ducts and pipes running through, it was 'easier' to fill with pink. I also had one cold air and warm air duct that used the entire ceiling joist cavity as the duct. I put pink under that, held in place by my hatchanneling, and some creative taping and stapling

The rest of my ceiling is double layer fire x (5/8's) drywall, GreenGlue, hatchanneling and Isomax clips.

P
post #14 of 100
Quote:
Originally Posted by petee_c View Post

Hi Outsider,

He said using more than 1 layer in ceiling joists is overkill. It works negligibly better than 1 layer, better to use the money in other ways to soundproof.

P

I believe a bag of S&S sound covers 60 sq ft. and costs about $35-40 at HD Canada.

4x8 sheet of 5/8th" drywall = $17ish at HD. (32 sq ft)

I would go for the 2nd layer of drywall (if u can do drywall) instead of 2 layers of S&S for the same price.

P
post #15 of 100
I agree with petee_c's last post, but disagree with the Roxul fellows assertions regarding mineral vs. fiberglass.

A few comments:

Adding drywall between the joists is more directed toward damping footfall noise. It's not quite as labor intensive as it may seem since the drywall can be cut 1/4" narrower than the joist cavity. Goes pretty quickly.

If anyone has data that says there is something better than the cheapest fiberglass you can get your hands on, please send it my way. I have yet to see any insulation installed in a wall test any better than cheap fiberglass. Having said that, fiberglass, mineral wool and cellulose are all fairly comparable.

Similarly, I have never recommended that anyone spend the extra money to go beyond R19 in a joist cavity. Technically it is better, but I have never felt the return on investment to be worth it. If there is data that supports a different position, I have yet to see it.
post #16 of 100
Quote:
Originally Posted by petee_c View Post

Hi Outsider,

I spoke to a tech at Roxul (in Milton) - number on the web or on the S&S packaging... He said that the mineral wool should be a bit better for bass control because it's denser than the pink stuff.

Ask him for the complete 3rd party lab report that clearly shows this. Send it on to me. If he is correct, I will mail you a $20 bill American (okay, it's not worth much anymore ).

Regards,
Terry
post #17 of 100
Quote:
Originally Posted by Terry Montlick View Post

Ask him for the complete 3rd party lab report that clearly shows this. Send it on to me. If he is correct, I will mail you a $20 bill American (okay, it's not worth much anymore ).

Regards,
Terry

Terry, I'll pm you their 1800 number. Please ask the questions yourself, and save your $20US. I just took his word for it, and please report back w your findings.

Peter
post #18 of 100
This has been discused for years, and we've looked at all available data. There just is no data that supports their assertions. That's Terry's point.

You can't blame the roxul guy. That's what he was told. You hear the same blanket assertions from the cellulose people and foam people. They are all told to tell people they have the best insulation.

The NRC in Canada put this all to rest in their big study IR 693. Low density is better than high density. Open cell is better than closed cell. Again in truth cellulose, mineral and fiberglass are all close, but fiberglass was the marginal winner in the low frequencies.

The good news is that fiberglass is not only the best choice, but the cheapest.
post #19 of 100
I have been searching around, and the general consensus is that Pink is the best bang for your buck in insulation, as far as sound isolation goes. Thanks to everyone for all of their knowledge!

But I do have some questions still. Just about to insulate by basement/HT, and I have been looking at all of the products available in my area. They are:
Pink R12: $0.35/sq ft
Pink R14: $0.56/sq ft
Pink Quietzone: $0.35/sq ft
Roxul R14: $0.50/sq ft
Roxul S&S: $0.57/sq ft

My questions are:
- Do i get an added bonus (or $0.21/sq ft added bonus) by going form R12 to R14? For both heat AND sound isolation. Keep in mind I live in Canada.
- If R14 is worth it, should I go with the Roxul? It is cheaper, easier to work with, is it any better/worse/same? From what I have read, it is basically the same.
- For interior walls, does the Pink Quietzone have any added benefit over Pink R12? its the same price, so I may as well use what ever one is better.

Thanks to everyone who replies.
post #20 of 100
I'm tired of hearing these claims from Roxul. Perhaps we should ban the word.
post #21 of 100
I agree with you Dennis.

From a practical soundproofing perspective, R12 and R14 are all equivalent. So I would vote for the Pink. If 2 points of R value is worth is to you, get the R14.
post #22 of 100
Thanks guys, R12 it is. Any thoughts on the Quietzone stuff for interior walls? From the manufacturers site, all I can find is that it doesn't really have any thermal properties, and outperforms absolutely everything as far as sound isolation goes. In other words, I didn't get any useful information.

Any benefit? Can't hurt?
post #23 of 100
Can't hurt
post #24 of 100
What increasing density does. Table 1 from the USG Density report (attached)

Measurably,
Andre

 

USG Density Report.pdf 263.7734375k . file
post #25 of 100
Nice article Andre, thanks for posting that.

The report describes what we've discussed. Increasing density does very little in the low frequencies. Any published variations are within test to test expected tolerances, even when testing the same sample repeatedly. The NRC in Canada doumented a slight advantage to the less dense fiberglass in the low frequencies.

High frequencies receive an improvement, as the NRC found also, but with a massive decoupled assembly like we build for theaters and recording studios, high frequencies are never the issue unless significant flanking is present.

STC is a mid to high frequency measurement, and the research spends a lot of time describing the benefits of office speech sound attenuation.

That was published in 1985 when USG was looking to make a case for the use of Thermafiber insulation.

For our purposes standard fiberglass is less expensive and better in the low frequencies where we need it the most.
post #26 of 100
There is a new 2" fiberglass panel available from Quest (www.questai.com) which has an absorption coefficient of .90 at 200 Hz and .73 at 125Hz. TL data is available down to 100 Hz (tests by Riverbank).

STC data from manufactures don't count in our application ... only TL numbers are useful.

Understand that for fiberglass panels placed on walls, their absorption is considerably diminished for off axis sound (ie, their full benefit is only available for direct, straight into the panel, reflections.) For more info, see Toole's "Sound Reproduction", 2008 (available on Amazon).
post #27 of 100
Hmm,

Im doing a dropped/suspended ceiling. I currently have roxul safe n sound installed between the joists and have lots of room left. Would there be any added benefit of throwing up some pink fiberglass on top of that (ie so it will be between the suspended ceiling and the roxul)

What are the thoughts on this?

Thanks a lot
post #28 of 100
So many of the assumptions here are that we are using DD + GG for our walls, which takes the higher frequency sound waves out of the question when considering insulation.
But lets assume that we are using either a drop ceiling, or simply a single layer of 1/2" drywall. So aside from the answer of "dont do it that way", would there be a benefit of using the safe n sound over pink fiberglass?
post #29 of 100
One more time...there is no advantage to Safe and Sound over standard fiberglass.
post #30 of 100
Thanks Dennis - however, i had already bought safe n sound and wondering if there will be additional benefit i thow pink over the safe n sound to help absorb a little more bass through the ceiling. I got the stuff so i have 2 options, either return the unused, or use it as mentioned above.

Thanks
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