# DIY sound proofing



## msrd (Dec 6, 2008)

Im about to start working with my contractor on building my home theater (8 seats)
I would like to know the steps for sound proofing the room

thanks


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## bpape (Sep 14, 2006)

Is the room already framed? If not, there are a lot of things that can be done reasonably to help quite a bit. 

Just remember that sound travels through the air and through the structure. 

Decouple the room from the rest of the house as much as possible. 

Seal ALL holes (outlets, switches, lights, etc.) or better yet, do them so they don't make holes in the sealed room

Use a solid core wood door with seals

Pay a lot of attention to how you're going to heat and cool the room as HVAC systems snake all through a house and transmit sound both ways very easily.

Bryan


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## chadcummings (Apr 26, 2008)

Another note on the AC. Do NOT use the metal ductwork, you want to use the ductboard and make sure you have some Z turns in it to reduce sound transmission.

There are a lot of ideas on the board and most are not incorrect, just not the prefered methods. Many people cool the room and then have an air return above their projector where others vent at the projector and pull from another part of the room. Both will work; however, one can cause condensation on the projector.

Best advice is read, read and read and when you think you know, post your thoughts to see what advice you can get.

That is what I have been and are currently doing.


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## bpape (Sep 14, 2006)

Agreed on the non-metal. Just also understand that ductboard won't provide isolation. The board needs to be inside a box structure with mating bends to provide the mass to stop bass passing directly through the ductboard.

In that type of construction, you can also use flex duct inside MDF boxing to provide the same effect.

Bryan


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## chadcummings (Apr 26, 2008)

Agreed.

I planned on running my ductwork inside my sealed room in the soffit area. This ensures plenty of isolation while the ductboard prevents the high freqs from running through the house.


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## Gregavi (Sep 22, 2009)

One Layer 1/2" drywall over 5/8" layer of drywall with Green Glue or Quiet Glue between the layers. Simple, effective. Not cheap, but less expensive than some methods that are not as effective. Staggered stud or double wall framing with the double drywall method.


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## Ted White (May 4, 2009)

I realize this is an old thread, however, people pour through old threads like this for insight. In general:

Decouple the new drywall surfaces from the original framing via a decoupling means.

Add Absorption, generally R13 or R19 fiberglass insulation.

Add mass. This is a bargain using standard $8 drywall. Use double 5/8"

Add damping. Different materials used for this.

These are the 4 elements in play with soundproofing. This article may help clarify: http://www.soundproofingcompany.com/library/articles/elements_of_room_construction/


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## uncle (Nov 29, 2009)

Hey Ted, 

Can you please explain to me why we want to build our soffit system after the room is framed and drywalled? If you're building a room within a room, why wouldn't you frame your soffit when your framing your room, then add your layers of drywall around the soffit system? Otherwise you'll have to drill through, cut holes through and attempt to securely mount the soffit over existing drywall.

I read in one thread that you and another fella (who was also in the sound isolation business) were instructing another poster to mount the soffit outside the drywall. But I never did hear the reasoning behind it. 

I understand that this is the preferred method, I'd just like to understand why this is preferred over framing the room with the soffit.

Thanks for your time.


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## Ted White (May 4, 2009)

Reasonable question. First, you and anyone else can send me a PM with an email address and I'll send you a couple of heavily illustrated articles on the topic. 

If the soffit is framing over a beam or ductwork then you would frame the soffit before drywalling as you said. 

If the soffit will have lighting and you don't want sound leaking out (or in) then you will need the ceiling and wall drywall completed. Just one layer of drywall would suffice. 

If the soffit is to house ductwork and act as a muffler then the soffit must be sealed on all four sides
_Posted via Mobile Device_


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## bpape (Sep 14, 2006)

There should be no need to 'cut holes and drill through' if you plan ahead. If you know where your soffiting will be, make sure there's a good place to attach to along that path prior to drywalling the ceiling.

After that, the only holes are those going through the framing, through the drywall, and into the mounting points. That's already pretty well sealed up. 

Bryan


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## uncle (Nov 29, 2009)

thanks Ted for those very informative pdf's. I now understand why we want to have a separate soffit system. Your handouts spoke about a dead vent. I take it that's the cold air return system? Can you speak some more about the dead vent system, it's purpose, different types of construction methods, etc....

Uncle


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## uncle (Nov 29, 2009)

Hey Bryan,

Do you know the load carrying capacity of the res bar? I curious about the lbs/sqft a proper soffit system would weigh. 

By proper soffit system I mean a partitioned soffit with venting on one side, sealed off from the electrical side with either OSB, or MDF. Then you would have your 2 layers of DW with GG on the exterior. 

Is there more heavy duty options to res bar?


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## Ted White (May 4, 2009)

Uncle,

Glad the articles helped. Soffits are generally quite long which gives us all that length to attenuate sound. Every foot of travel through the soffit reduces the sound more and more. Soffits are long and thin.

The Dead Vent is short and squat. Used if soffits aren't available / convenient. Both soffits and Dead Vent can be used to exchange air with the rest of the basement OR to interface with the main HVAC system.

Side note: I wouldn't spec resilient channel ever. The fact is there is no single standard for its construction. Some is 20 gauge, some 25, some in between. Some are slotted for flex, some are solid, some have holes.

Again, there isn't a standard for strength or flexability. Drywall Furring Channel, on the other hand, is specified by the Steel Stud Manufacturers Association, along with all other steel framing components. 

This method of decoupling is effective if the steel can act like a spring. Since there's no manufacturing standard, the net result is that you have no idea if the resilient channel is too stiff (no spring) or too loose (no spring).

Much better to use the commodity resilient sound clips for a buck and a half and Drywall Furring Channel for $3 for a 12 foot stick. For a little over $40 you can install a ceiling with these steel clips + channel that would put any resilient channel ceiling to shame.


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## bpape (Sep 14, 2006)

uncle said:


> Hey Bryan,
> 
> Do you know the load carrying capacity of the res bar? I curious about the lbs/sqft a proper soffit system would weigh.
> 
> ...


Sry - not sure what you're asking here.

If you do a set of RSIC-1/Whisper clips at the ceiling edge of the soffit, it's not an issue overall.

Bryan


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## uncle (Nov 29, 2009)

Gottcha, 

thanks again fellas. 

Uncle


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## Ted White (May 4, 2009)

Part of the real issue is that res bar has no spec and no ratings. The Drywall Furring Channel that is used with clips, on the oher hand, is rated by the SSMA.


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## uncle (Nov 29, 2009)

So I've only seen pictures of this product on line. Are the clips used in conjunction with the furring channel? or are the clips just 2" pieces of the furring channel used for spot contact?

Ya, I used res bar in my last theater, meh. However I do like the look of this DW furring channel. It looks much better than the res bar I used. I never knew DW furring channel and clips existed.


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## Ted White (May 4, 2009)

Clips are installed in an array. Then the Drywall Furring Channel is inserted into the clips


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## uncle (Nov 29, 2009)

Aaaahhhhhh, 

Two piece system, spring loaded, excellent....


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## Ted White (May 4, 2009)

Spring is the operative word. A spring will bring great isolation benefits. Resillient channel can sag, and just hang there. No spring. Or be short circuited, and become rigid. No spring.

The clip + channel system really can't be compromised, unless you really, really tried.


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## bpape (Sep 14, 2006)

Zactly. It's a system to be installed. One without the other is meh to OK depending on what you do.

Bryan


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## Mjulnir (Apr 8, 2009)

Any DIY combo with yellow glue to make this stuff?


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## Ted White (May 4, 2009)

Mjulnir said:


> Any DIY combo with yellow glue to make this stuff?



?? Sorry, not following the question.


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## bbieger (Sep 15, 2009)

Just installed my clips and channel. could not be easier really. There is no way you are going to replicate the clips, they are pretty springy and very strong which is a hard combination to create. Don't forget, you can always install blocking and run the channels parallel to the joists if you are worried about loss of headroom. That is how my install went.. total loss of headroom = 1/4 inch. 

Total system cost was just a hair over green glue alone. From what I was told it is much more effective but Ted could probably speak to that.


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## Ted White (May 4, 2009)

Clips are post stamp annealed spring steel. Serious metal. 

That 1/4" is seriously tight tolerances. Wow.

Actually Decoupling (clips) and Damping (green glue) are different functions. Both offer great benefits.


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## bpape (Sep 14, 2006)

Nicely done. That's a good job to get down to only 1/4". 

Bryan


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## Ted White (May 4, 2009)

For those reading, however, that's a very, very tight tolerance with zero margin for error. If it works, that's excellent, obviously. If it fails, there will be buzzing, conduction and limitation of the flex of the channel. 

For those who are considering this, please keep this in mind.


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## Oggie (Dec 17, 2009)

Ted White said:


> Clips are installed in an array. Then the Drywall Furring Channel is inserted into the clips


Thats so much room lost with how thick that insulation is. I bought something different from home depot about a year agoo....can't remember what its called but its brown and about half an inch thick. I used it to sound proof my recording studio and it works incredibly well. I get about 80-90% sound reduction from outside.


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## Oggie (Dec 17, 2009)

oh, and i sealed it with silicone caulking. worked well for a DIY home studio. might work for your home theater too.


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## Ted White (May 4, 2009)

I'm glad that worked to your satisfaction. You're referring to soundboard, or one of a few other names for it. Again, glad that worked for you but the lab test numbers are not favorable. 

Too dense to decouple, especially after you drive screws through it. 

Also too dense for cavity resonance attenuation. 

Not dense (massive) enough to contribute weight like drywall does.

So soundboard does a bit, but other products hit the mark better for most.


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## DavidLuke (Apr 13, 2010)

How about using a layer of foam and quietwood or quietrock instead of the channel and drywall?


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## Ted White (May 4, 2009)

Hi David,

Since this is a ceiling appication we want significant decoupling from the joists. Foam doesn't come close in this respect. 

Regarding the use of a factory-damped drywall panel, any pre-damped drywall is simply layers of standard boards and damping compound. There is simply no mystery to the materials. So the decision to use these pre-damped boards comes down to:

Price (less is better)
Mass (more is better)
Damping (more is better)

Generally you will always be able to field assemble a more massive, more damped and less expensive panel. An additional plus is that field assembly will allow you to overlap seams between the drywall layers.


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## bbieger (Sep 15, 2009)

The channel is the way to go. Not a whole lot more than a whole mother layer of drywall and allot more effective
_Posted via Mobile Device_


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