Anyone use Certainteed Silent FX (vs. other sound reducing board?) - AVS Forum
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post #1 of 17 Old 06-22-2011, 04:17 PM - Thread Starter
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Looking to add 5/8th over existing board w/GG as part of larger water damage repair and given the bedroom is right next to the freeway (and it is verrrrry loud) and I can't seperate the site walls with clips or double wall, I wanted to get the 'double up' by doing sound reducing drywall along with the GG.
QR seems to be the most commonly discussed product but a local supplier mentioned their primary product is certainteed and just carry the QR EZ snap now. Said something about mold/moisture issues as to why they don't cary 525 or the others but didn't have concrete information.
Silent FX seems to essentailly be two sheets of drywall with treated/moisture resistant paper with GG (branded GG, not GG-like product) already applied.

I can't find much marketing material and their site simply says STC of 50 or greater. Sales rep says it is $65 for the 5/8ths (posting as I don't see a MSRP so I'll just assume that is MSRP) which is more than QR EZ.
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post #2 of 17 Old 06-23-2011, 11:20 AM
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Quote:
Originally Posted by curtisb View Post

given the bedroom is right next to the freeway (and it is verrrrry loud) and I can't seperate the site walls with clips or double wall.

QR seems to be the most commonly discussed product but a local supplier mentioned their primary product is certainteed and just carry the QR EZ snap now.

Hi Curtis,

I have two bits of information:

#1
I've done quite a bit of research and testing (both for acoustics and for installation) on my own of the Silent FX board and although it may achieve similar performance to the QuietRock ES board, it will cost you more in labor if you are hiring a contractor to do the work.

QuietRock ES was developed and is manufactured as a response to contractor input, so the installer only has to cut through one layer of face paper to score and snap the board vs. cutting through three layers of paper for any other damped board, including some of the other QuietRock models. You may have to fork out more money for the contractor install when using Silent FX.

The QuietRock manufacturers do carry a mold resistant product if you need that, but unless it is necessary it's much less expensive and more effective to use QuietRock ES. In that case, you can also you QuietGlue Pro instead of Green Glue, as it performs the same or better and may be less costly.

Feel free to send me a message if you have specific questions regarding the performance of QuietRock on different assemblies.

#2
Because this is an exterior wall you not only have to worry about the wall itself, you also have to worry about windows and doors. Windows and doors, although they may be a much smaller total surface area of the wall vs the wall itself, can cause major decreases in the amount of achievable noise control through the exterior wall partition.

I have an Excel sheet calculator that I have made, based on equations in Harris's Handbook of Acoustical Measurements and Noise Control, that allows you to calculate the composite STC (STC rating has to do with the noise control) of you complete assembly. All you need are the surface areas of each component (i.e. wall, windows, doors).

Just let me know if you need/want it via email/message, and I will send it along. Really useful.

I apologize for the length here. Just wanted to be thorough/detailed enough to help out
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post #3 of 17 Old 06-23-2011, 11:42 AM
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Nothing will be cheaper than using standard off-the-shelf 5/8" drywall and field damping. Assuming similar damping capacities, the solution that has more mass wins.

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post #4 of 17 Old 06-23-2011, 12:02 PM
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Quote:
Originally Posted by curtisb View Post

Said something about mold/moisture issues as to why they don't cary 525 or the others but didn't have concrete information.

I have never heard of such a thing and doubt that is the case.

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post #5 of 17 Old 06-23-2011, 12:07 PM
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Originally Posted by Ted White View Post

Nothing will be cheaper than using standard off-the-shelf 5/8" drywall and field damping. Assuming similar damping capacities, the solution that has more mass wins.

Technically, Curtis, this is not true for all cases.

If the frequency range of interest is in the mid- to high- frequency range (like the average automobile) then that is where damping truly overcomes mass, even multiple layers. I have done a few research studies at two different laboratories that illustrate this if you would like to look at them.

A very large vehicle may radiate lower frequencies when driving down the road in front of your wall, but the fundamental sound radiation frequency from most vehicles is no lower than 200 Hz, which is a high enough frequency (tone) that the damping will do better than double or possibly even triple the mass.

Again, I have laboratory testing to show this, if you need, and there are MANY examples of traffic/vehicle noise available in published literature.

Contrary to popular belief, mass is NOT always the answer.

Sorry Curtis, but I really had to respond here. This isn't the place for a debate really. Just want to make sure that correct TECHNICAL information is shared.
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post #6 of 17 Old 06-23-2011, 12:11 PM
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Assuming similar damping capacities, The solution that has more mass wins. Adding a sheet of 5/8" is better than adding a sheet of 1/4?

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post #7 of 17 Old 06-23-2011, 12:19 PM
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i like where this is going.

"The main reason Santa is so jolly is because he knows where all the bad girls live." - George Carlin
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post #8 of 17 Old 06-23-2011, 12:20 PM
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It really does depend on more than just thickness/density. I have been recently doing some practical testing combined with theoretical modeling of the transmission coefficient/transmission loss through single- and double-leaf partitions.

Depending on the loss factor/shear modulus of the sheet AND on the frequency range of interest, yes, a 1/4" sheet may perform better than the 5/8" sheet.
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post #9 of 17 Old 06-23-2011, 12:22 PM
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i like where this is going.

George Carlin. He's a genius. Love that quote
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post #10 of 17 Old 06-23-2011, 12:22 PM
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Meanwhile, back at the ranch, we're generally interested in stopping low frequencies and avoid 1/4" drywall.

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post #11 of 17 Old 06-23-2011, 12:28 PM
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Quote:
Originally Posted by Ted White View Post

Meanwhile, back at the ranch, we're generally interested in stopping low frequencies and avoid 1/4" drywall.

Yes, back at the ranch with the home theater I am certainly more interested in stopping the low frequencies. Because really, my ranch is out in the middle of nowhere (at least in my imagination) and I don't have to worry about traffic noise.

However, here at Curtis's house I'm more interested in his traffic noise problems and the most effective solution for those
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post #12 of 17 Old 06-25-2011, 05:42 AM
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Now, this is really starting to get interesting.....

Follow my thread here
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post #13 of 17 Old 09-14-2011, 07:01 AM
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I used the product on a couple of installations and found it was not too big a deal to cut, granted I was using near full sheets most of the time. When a product has inherent mold and mildew resistance along for the ride I thought that was only a bonus, talked to the company and the core is standard green glue, I used the GG sealant and some clips on one shared well (townhome) as well. Didnt meter it before but the client was estatic with the results.
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post #14 of 17 Old 09-14-2011, 07:32 AM
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Glad that worked for casual noise. For maximum performance at minimum cost, double 5/8" drywall and a field application of damping compound will work best.

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post #15 of 17 Old 09-07-2013, 04:30 PM
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QUICK ANSWER: Airborne noise control in wood construction requires four elements to be successful.

1. The MASS of the wall (gypsum board typically) should be as FAR APART as possible. Eight inches is a popular distance for apartments.

2. The STRUCTURE of the wall should be DISCONTINUOUS. A double stud wall with One inch or more of space between the two wall base plates.

3. The CAVITY of the wall should be FILLED WITH FIBER GLASS insulation (the regular pink stuff used as R-11 to R-38 thermal insulation).

4. THOUGHT must be used to eliminate FLANKING PATHS such as Back-to-Back Outlet boxes (stagger them 24" apart in different wall cavities and back them up with a 8" to 14" square of sheet rock behind the outlet and in front of the fiber glass. Avoid plumbing in party walls and isolate all pipes with soft material to avoid rattling on any wood. Be SMART to keep it QUIET.

Certainteed Silent FX is a good product but by itself without items 2, 3, 4 above it will add very little to a STC value. For your exterior wall along a noisy street I recommend you remove the interior wallboard or plaster, fill the 2 x 4" wall cavity with Owens-Corning R-13 or Certainteed insulation with 0% voids (a 2% void in any wall insulation increases heat loss by 20% in tests at a leading lab), apply U. S. Gypsum Resilient Channels across the studs with screws and then screw on U. S. Gypsum or Certainteed 5/8-inch type X drywall, then tape and texture and paint. You will need to adjust your wall electrical outlet boxes outward to accommodate the new 1/2" wider wall. You will need to change the trim around your windows to be 1/2" wider to accommodate the 1/2-inch Resilient Channels. Avoid flanking paths and you will have a wall of STC 49 or greater (depending upon your outside wall surfaces) using Resilient Channels and insulation.

NOW HERE COMES THE PROBLEM with single stud walls using Resilient Channels. If you hang a picture, a clock, or something on the wall you can EASILY CREATE A FLANKING PATH. It happens when you nail through the drywall and into a stud on the resilient channel side of the wall to hang something. The nail provides a huge path for sound to travel because it FLANKED the assembly. So forget nailing on ceiling moldings or baseboard molding -- GLUE THEM INSTEAD. Here is a solution to hang things, do what museums do by using a hook and wire to suspend paintings or wall objects from the ceiling molding. If it is heavy, put it on a pedestal on the floor.

When in doubt -- see item number 4 above. It is the tricky part.


NOW MORE SOLUTIONS FOR NOISE CONTROL IN WOOD FRAME BUILDINGS...

Noise Control Types and Ratings

Noise Control in buildings addresses two issues. (a) Airborne noises (speech, television, street noise etc.) and (b) Impact noises (people walking upstairs, knocking on a door).

The building industry has developed testing standards to make it possible to compare "apples and apples" with a single rating number. A wall assembly or a floor/ceiling assembly is tested in a specialized laboratory to determine the rating numbers for Airborne Noise (STC) and Impact Insulation Class (IIC) Noise.

The standard test method for Airborne Noise results in a Sound Transmission Class number which is called a STC Value. The Higher the STC Value the better.

The standard test method for Airborne Noise results in a Impact Insulation Class number which is called an IIC Value. The High the IIC Value the better.


What STC and IIC Values

A STC Value of 55 and a IIC Value of 55 are calibrated to result in the same Excellent Class of sound control performance. Here is a table to guide you in residential single-family and residential multiple-family wood framed buildings.


PREMIER CLASS of Noise Control: STC and IIC ratings of 60+

EXCELLENT CLASS of Noise Control: STC and IIC ratings of 55 to 59.

GOOD CLASS of Noise Control: STC and IIC ratings of 50 to 54.

FAIR CLASS of Noise Control: STC and IIC ratings of 45 to 49.

POOR CLASS of Noise Control: STC and IIC rating of 44 or less.


Two leading Sound Control Laboratories are the Owens-Corning Granville, Ohio lab and the U. S. Gypsum sound testing reports. These two companies are my favorite sources of reliable noise control data. I recommend them to you. They have the highest integrity and are conservative in their published results. They also consider fire ratings of walls too.


CONCERNING THICKNESS OF MULTIPLE LAYERS OF GYPSUM BOARD AND FIBER GLASS

1. In tests at major labs, Double Stud Walls with one-inch separation of the two walls have a STC 58 when filled with 7-inches of fiber glass insulation. With one blanket of R-13 3-1/2" fiber glass the STC is 55. With no fiber glass insulation at all the STC drops to STC 47. This points out how fiber glass insulation becomes very valuable once a DISCONTINUOUS wall is built. This is generally a One-Hour rated fire wall with 5/8" type X gypsum board is used.

2. When more gypsum board is added to an uninsulated version of this Double Stud Wall the STC only increases a little. Surprisingly, if a second layer of 5/8-inch gypsum board is added on top of the first layers on both sides of the wall the STC only reaches STC 51. So fiber glass insulation is a much better idea than doubling up the mass with more gypsum board.

3. An even more interesting fact is that gypsum board layers of different thicknesses such as 1/4", 3/8", or 1/2" applied OVER 5/8" type X gypsum board results is better STC performance than a second layer of 5/8" type X gypsum board. In this case, it seems that the two different densities of gypsum board applied together on each side of the wall vibrate out more sound energy than (the process is the sound pressure waves vibrate the gypsum board and the sound energy is turned into heat). My favorite multi-family wall is a combination of 3/8" and 5/8" type X wallboard on both sides of the wall assembly with the cavity stuff with fiber glass. This results in STC values in the 60 to 63 range.

4. Finally, another surprise. Moving a layer or two of gypsum board into the middle of the Double Stud Wall assembly and filling the cavities with insulation REDUCES the STC ratings of the wall assembly. Adding more gypsum board to the middle of the wall violates the physics of keeping the MASS of the wall as FAR APART AS POSSIBLE.

So the basics are always --

A. Build discontinuous construction
B. Place the mass as far apart as possible
C. Fill the cavity with fiber glass insulation
D. Be very smart about avoiding flanking paths for sound.

Over past 45 years as I have participated in the building industry as well as in the computer industry and I have found one common truth to both. "It is impossible to make things Idiot Proof because Idiots are so darned clever."

In the construction industry mistakes are made by "Ignorance." In the computer industry mistakes are called EBC&K -- An Error Between Chair & Keyboard.

Are they both the same?

BE SMART FOR EFFECTIVE NOISE AND THERMAL CONTROL.
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post #16 of 17 Old 09-07-2013, 07:10 PM
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Just wanted to KINDLY (no harm intended) make you aware of this caveat of STC ratings:

"The STC number is derived from sound attenuation values tested at sixteen standard frequencies from 125 Hz to 4000 Hz."

HT audio produces MUCH lower (and higher) frequencies than those tested for STC ratings. Therefore, STC ratings are a decent starting point for sound isolation but I must remind all that they don't test below 125Hz which is actually where most of the sound proofing "issues" arise within dedicated HT's. The methods used to achieve high STC ratings (insulation, adding mass, etc.) will in effect be the same sound-proofing techniques needed for low frequency isolation, but usually other construction methods, such as mechanical isolation [decoupling] of ALL components of the floor/ceiling/walls between the HT and the surrounding building components, needs to be adhered to in order to keep the flanking and robust lower frequencies out of the main structure of the building.

Here is another blurb to reiterate my statements above:

"The measurement (STC) is accurate for speech sounds, but much less so for amplified music, mechanical equipment noise, transportation noise, or any sound with substantial low-frequency energy below 125 Hz. Sometimes, acoustical labs will measure TL at frequencies below the normal STC boundary of 125 Hz, possibly down to 50 Hz or lower, thus giving additional valuable data to evaluate transmission loss at very low frequencies, such as a subwoofer-rich home theater system would produce."

And furthermore since the STC rating is a number derived from a reference contour, the resulting integer is based upon a curve, therefore an assembly (wall/floor/ceiling) with a certain STC rating may not perform the same in attenuating the same frequencies as another wall using different materials and construction methods but with the same STC rating. Sound pressure is a very dynamic annomily to deal with and attenuation isn't like hitting the mute button, it's more like waving your hand and hoping to catch as many frequencies as you can before it hits your neighbor's (or sleeping family's) ears when you're trying to watch The Dark Knight at 11pm.
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post #17 of 17 Old 09-09-2013, 04:39 AM
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In one of the above posts there's a lot of info. No need to parse words, but inserting as much cavity depth as possible is usually very inconvenient. Better to add more mass.

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