# Wall soundproofing add ons?



## chrapladm (Jun 17, 2009)

I am probably not going to be able to do my ideal HT room but the wifey has said she wouldn't mind me doing a HT room in the existing living room we have.

Now one of the questions I have is when others use an existing room and want to add green glue and another layer of drywall do the just add straight onto the existing drywall?

My room has a main entry door, a hallway and a entry to the kitchen. I also have a big window on the same wall as the entry door. So like I said I just have to work with what I have. I do have one wall that doesn't have any openings on it and that is what I plan on making the viewing wall.

I will try and do a google sketchup or atleast a picture that will help explain. I was just thinking of doing a single double layer of drywall with green glue for sound absorption. SO that is the first question I am trying to figure out.

I also forgot to ask what is the next best thing I could do for soundproof absorption? I wont be doing the decoupled wall so I was thinking of maybe a resilent channel and double drywall but not sure.

I am thinking I will only be able to do the minimum like a double drywall or maybe the staggered stud but I am trying to not lose very much interior space. I know with the extra layer of drywall I wont lose much space. I think I have 10mm thick walls so I might try and do a double 16mm walls with "green," glue. SO that means I would get rid of the 10mm wall to start and replace it with a 16mm.

Is it going to be night and day difference if I added resilent clips hat channel to the 16mm DD versus just having the 16mm DD?

I will take a picture as soon as I can. I have other questions but I am sure it would be easier if others could see what I am talking about.


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## Ted White (May 4, 2009)

You would simply add the damping material and new drywall over the existing. Screw to the studs
_Posted via Mobile Device_


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## chrapladm (Jun 17, 2009)

Thanks now the other question is:

I know that going from no sound absorption to decoupled walls would be night and day difference. But is there a huge difference between having resilient channel and staggered stud?

I am going by your website Ted and I was just trying to do whatever I could with the minimalists amount of interior space loss. Now losing an inch on each side is fine with me but I was just wondering if there was a huge difference between the two I mentioned.

And now that I look it seems wouldn't the loss of interior space be the same or close to if I did staggered studs vs resilient clips and hat channel?

If this IS true then I think I should be asking how much space do you lose when using the resilient clips/hat channel versus resilient channel GG?


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## Ted White (May 4, 2009)

If you could swing the double stud wall I would highly recommend it. The low frequency isolation is excellent.
_Posted via Mobile Device_


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## Ted White (May 4, 2009)

Also the resilient channel is problematic and I'd encourage you to pass on that. Resilient channel and resilient clips are two different systems.
_Posted via Mobile Device_


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## chrapladm (Jun 17, 2009)

OK I was just trying to compare the difference between your two systems described on this page:
http://www.soundproofingcompany.com/library/articles/elements_of_room_construction/

On your more effective less effective picture I was trying to see what the difference is on absorption between the middle 2? "Resilient clips/hat channel w/ GG vs staggered stud w/ GG

Is there a huge difference absorption wise? 

And when it came to losing interior space when applying these two different systems are they about the same give or take an inch?


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## Ted White (May 4, 2009)

They are similar in depth while clips provide better decoupling. Helps with low frequency isolation.
_Posted via Mobile Device_


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## chrapladm (Jun 17, 2009)

Ok I think I will look more into the resilient clips/hat channel system more. I do plan on having a crazy all out low extension subwoofer so more absorption the better. PLus with all this absorption I still will have a huge window in the room that will be the weakest link.

But like I said I am just trying to do what I can.


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## chrapladm (Jun 17, 2009)

I know this is an old thread of mine but I wanted to ask another question in regards to drywall.

I have had a closer look at my walls and noticed that behind my sub I never saw a crack in the wall. The sub was 6ft tall and I didn't notice till I sold the sub that there was a crack from the floor to the ceiling. And there is also a crack about 2-3feet long horizontally. Now all these cracks are where the drywall has been mudded together. SO there aren't any cracks anywhere else but I am assuming that is where everyone who has the same problem gets their cracks at.

Now I cant don't my whole room with staggered studs and double drywall. I was thinking that I would like to cover up the cracks though and help aid in this not occurring again. The drywall that was cracked along the seems was only 10mm drywall. Dont know if that matters or not. 

I was thinking of doing a double drywall with green glue but using 16mm sheets in the future. I know this wont due much for my horrible floor plan but if it can help the walls from cracking that would be great.

Any other thoughts about this idea Ted or others?


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## SAC (Dec 3, 2009)

Generally, you are not going to substantially change the sound transmission through a boundary without adding significant mass -regardless of what quite a few 'magic' products want you to believe.

And it doesn't matter what you add to the wall if you don't address *ALL* flanking vectors, as the sound transmission is only as strong as its weakest link.

May I suggest that instead of positing all sorts of creative techniques, that you instead stick to the tested and verified approached described below. Simply analyze the construction of your existing wall and match it to one of he various design systems described in the guides below. Determine the precise amount of additional isolation required, and then proceed, remembering that you MUST address the flanking Pecos - else all of your effort is wasted.


Here is a generic listing of downloadable documents available from the NRC on Isolation methods. The NRC is an excellent source of tested construction methods. Pay particular attention to the doc regarding flanking paths.

You first need to determine exactly how much isolation you require: (max internal level in db SPL - maximum external level in dB SPL) = minimum amount of isolation required.

Owens Cornng Acoustical Wall Insulation Design Guide 
(http://www.owenscorning.com/worldwide/admin/tempupload/canada/30011340.pdf)

NRC (National Research Council) docs (Choose the docs that are appropriate to the construction type):

Gypsum Board Walls: Transmission Loss Data
By Halliwell, R.E.; Nightingale, T.R.T.; Warnock, A.C.C.; Birta, J.A.
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir761/ir761.pdf

Sound Transmission Loss Through Concrete and Concrete Masonry Walls
by Albert Litvin and Harold W. Belliston
www.cement.org/bookstore/profile.asp?itemid=RD066

Sound Transmission Loss of Masonry Walls
by Warnock and Monk
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/brn/brn217/brn217.pdf

Sound Transmission Loss Through Drywall and Block Walls
by Warnock
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir586/ir586.pdf


Flanking information:

Controlling Interoffice Sound Transmission Through a Suspended Ceiling
by R.E. Halliwell and J.D. Quirt
www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc33097/nrcc33097.pdf

System Details That Work (Leaks and Flanking)
by David Quirt
www.nrc-cnrc.gc.ca/obj/irc/doc/leaks-flanking.pdf

Guide for flanking sound transmission in wood framed construction - airborne sources
by Nightingale, T.; Quirt, J. D.; King, F. 
http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc49468/nrcc49468.pdf

Airborne Sound Insulation in Multi-Family Buildings
by J.D. Quirt and T.R.T. Nightingale
http://www.nrc-cnrc.gc.ca/obj/irc/doc/ctu-n66_eng.pdf


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## chrapladm (Jun 17, 2009)

Thanks for the reply.

I hoped that fixing one of the walls would help but I have alot things against me already so I wasn't holding my breathe. I cant build my dedicated room for another 2 years or maybe 3. I have been listening to movies and music using only my SLA's which just have 3x5's for midrange duties.

Definitely need to use a sub but I have not bothered to connect it, due to fear of ruining walls even more. Sadly I have two more subs coming but they will clearly destroy my walls so they will probably just sit in their box unopened.:crying:


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## Ted White (May 4, 2009)

Single partition solutions are always going to be very limited in isolation due to flanking. This is more true in the lower frequencies. If you want to repair that wall, certainly another layer of drywall will accomplish that. It would be a waste to apply a damping compound in that repair, however.


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