# Question for the HTS experts



## LaserDisk (Nov 21, 2010)

Hi HTS fans

I am most concerned with sound from my under construction HT bothering my neighbour’s as our homes are built pretty close together. My home is typical Florida concrete block construction with furring strips on the block and then sheet rock. Would it be best in my case to use Rockwool or Corning 703 between the furring strips and cover the walls with Quiet Rock? Any other suggestions please? I also plan to use base traps and other interior treatments.


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## bpape (Sep 14, 2006)

Either will work just fine. The best thing you could do is increase the thickness of the firring to make the cavity deeper which will drop the resonant frequency of the cavity. 

Bryan


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## LaserDisk (Nov 21, 2010)

The distance to my neighbour is such that I can’t go with a wider room therefore; unfortunately, the width of the room is critical. I’m trying to scrape every inch I can get for interior space for speaker placement. Quiet Rock is advertised as 8 times denser than normal sheet rock and with the combination of the Rockwool and Quite Rock I can’t come up with a better solution - if you all think it’s a good one.


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## bpape (Sep 14, 2006)

Can you spare 1.5" overall? If so, then use your normal firring on the concrete - then add another set of firring perpendicular to the ones on the concrete. Screw the QuietRock (or 2 layers of drywall with Green Glue) into the areas of the 2nd set of firring only - not anywhere that it would go through into the first layer. That will let the 2nd layer flex and act as a 'poor mans' version of clips and channel.

That minimizes surface contact and lets the firring flex to help turn some of the waves into motion - thereby minimizing transmission to the structure itself.

Bryan


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## LaserDisk (Nov 21, 2010)

Thanks for the great idea Bryan. Would you still use Rockwool or Corning 703 in-between the furring strips? Also, do you know if acoustic glue or Green Glue would be strong enough to attach the QuietRock to the furring strips rather than sheet rock screws? I would think that would even provide better isolation and flex.


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## bpape (Sep 14, 2006)

Green Glue is kind of a misnomer. It's not really a glue. You still need to use screws. Even if it were, I wouldn't trust just glue for something that's going to move like that. 

Yes - you'd still insulate in the cavities as much as possible. Just use a lighter density mineral wool. No need or performance gains to be had in that thickness from the extra money for 703 or heavier mass mineral wool.

Bryan


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## LaserDisk (Nov 21, 2010)

Thank you very much Brian for your expertise. :T

Sandy


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## LaserDisk (Nov 21, 2010)

Bryan,

Yesterday I watched several videos on YouTube of QuietRock installations and noticed in all that the QuietRock was installed directly to the studs. Wouldn't it be more effective to install QuietRock to Genie Clips or IsoMax clips to decouple it from the studs?


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## bpape (Sep 14, 2006)

Certainly. Clips and hat channel provide an additional layer of isolation in addition to the mass of the quietrock. Personally, if time isn't an issues, I think 2 layers of standard drywall and Green Glue is a better solution for less money. 

Bryan


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## ALMFamily (Oct 19, 2011)

I totally concur with Bryan - I originally had plans to use QuietRock. I then checked into the price -$80 a sheet. Way more cost effective to do DD and GG as well as more mass as Bryan said......


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## LaserDisk (Nov 21, 2010)

$80 a sheet, I'm sure it's worth it, but it makes you think doesn't it? 

My concern with the Green Glue and clips method, will the clips and hat channel support two layers of 1/2" or 5/8" sheet rock. The clips are rated at 45 - 60 lbs max with 22 ga steel furring. According to the chart below, 2 layers of 4' x 10' x 1/2" would weigh 136 lbs and then there's the Green Glue, sheet rock screws, tape, mud, paint and . . . I guess that's why in the YouTube videos you see them nailing directly to the studs.

According to United States Gypsum (www.usg.com), standard drywall weighs about 3.4 lbs per sq ft per inch thickness. Water resistant drywall (greenboard) weighs about 3.9 lbs. per sq. ft. per inch thickness. Firecode C drywall weighs about 4.2 lbs. per sq. ft. per inch thickness. These are approximations, as the ratio of core vs. covering varies for different thicknesses, thereby varying the exact weights. So, 1/2" thick standard drywall weighs 3.4 x 0.5, or 1.7 lbs per sq. ft.

4' x 8' x 1/2" thick sheet weighs 1.7 x 32 s.f. = 54 lbs.
4' x 10' x 1/2" thick sheet weighs 1.7 x 40 s.f. = 68 lbs.
4' x 12' x 1/2" thick sheet weighs 1.7 x 48 s.f. = 82 lbs.
5/8" thick standard drywall weighs 3.4 x 0.625 = 2.2 lbs per sq. ft.
4' x 8' x 5/8" thick sheet weighs about 70 lbs.
4' x 10' x 5/8" thick sheet weighs about 88 lbs.
4' x 12' x 5/8" thick sheet weighs about 105 lbs.


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## bpape (Sep 14, 2006)

If you look on the PAC website, they have 2 different layouts for how many and how to arrange the clips depending on what thickness and number of layers you're doing. Also remember that the clips and channel are likely rated on a per unit basis so there's going to be a lot more than 1 clip and 1 channel per piece of drywall. 

On the usage chart in an 8' tall room, IIRC, there are 4 channels running horizontal so even with 2 layers of 1/2" at 100 lbs (4x8), that's still only 25 lbs per channel over that 4' width.

Bryan


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## ALMFamily (Oct 19, 2011)

Another suggestion I heard was to make the 1st layer OSB and the 2nd layer drywall. The STC rating for OSB and drywall are pretty similar. Hang the OSB on the res channel and make it so it rests on the floor so that you use the floor to help support the weight. Then, hang the drywall as normal and seal the bottom gap with a noiseproof sealant. 

This is how I am planning to soundproof my room - I will defnitely plan to post how it works out.


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## bpape (Sep 14, 2006)

First, use RSIC-1 clips and hat channel as opposed to Resiliant Channel. You'll get better performance plus RC is pretty easy to short out with a couple misplaced screws. Pretty tough to mess up RSIC-1 and hat channel.

You can do MDF if you need to purely for mounting purposes - otherwise, drywall is cheaper for essentially the same performance. Regardless you don't want any of the layers really tight to the floor or ceiling. Not big gaps but not touching. The idea is to allow it to move and not be restricted by rubbing on floor or ceiling. Make sure to caulk all 90 degree junctions.

Bryan


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## ALMFamily (Oct 19, 2011)

bpape said:


> First, use RSIC-1 clips and hat channel as opposed to Resiliant Channel. You'll get better performance plus RC is pretty easy to short out with a couple misplaced screws. Pretty tough to mess up RSIC-1 and hat channel.
> 
> You can do MDF if you need to purely for mounting purposes - otherwise, drywall is cheaper for essentially the same performance. Regardless you don't want any of the layers really tight to the floor or ceiling. Not big gaps but not touching. The idea is to allow it to move and not be restricted by rubbing on floor or ceiling. Make sure to caulk all 90 degree junctions.
> 
> Bryan


Sorry, I misspoke in my original post - I am not doing res channel -I am doing Whisper Clips (from John and Ted) and hat channel.


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## bpape (Sep 14, 2006)

That'll work!


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## LaserDisk (Nov 21, 2010)

Thanks Guys. Now that we have the walls taken care of, how about the floor. The floor will be over a poured slab. I read somewhere that it is best to put down a hardwood floor (rather than a rug) and put a rug over the hardwood. What's your thoughts on the floor under-layment so as not to couple the floor to the walls?


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