Soundproof wall?

Building a wall against our side of a brick partition wall. The plan was to put 2x3 framing with 2" of soundrock 60 or 703 batts.
Since they fit in between the framing, doesn't this allow sound through the 2x3 since there is no soundboard behind it?
Is there a better option?

 

Read up on how to construct sound reducing walls. In your case the studs would be installed so they don't touch the brick wall with an air gap to prevent the direct transmission of noise. For greater sound protection another stud wall is constructed with it's studs not touching the other wall.

 

I guess what I meant was that where there is a stud there is no soundproofing board, is just wood.
doesn't that allow sound through every 24" depending on stud?

Also the rockboard is 24" wide. Usually the stud is 24" OC. Isn't that too tight for the board? By 1.5"

 

Things must be different in Canada, neither 24" OC spacing nor 2x3 walls are common here.

 

As Pilot said do some research.
I am not a pro at this but my understanding is that you want to de-couple the surfaces.
So I would put your soundproofing board against the brick wall and build your 2X3 wall in front of it.

 

Let's go back to the beginning, what is the situation that you are trying to resolve and please explain where this is going and how does the brick wall fit into the equation?

Maybe it's just me but I don't know enough about what your wanting to do to offer good advice!

 

It's a partition wall built out of concrete blocks a long time ago. Wall was just plaster and metal grid directly on the brick. There is no air gap, the other side of the brick is the neighbour's inside
​​of their house.
Sound is coming through from the neighbour's lounge, kitchen, laundry room etc.
there's a bedroom on our side to soundproof but we may end up doing the whole wall during the renovation.
2x3 walls are not common at all but the board is 2" thick so no need for a 2x4
replacing the wall in a renovation so want to put in sound proofing.
16" walls are common but the Rockboard is built for 24" walls.
Same question applies - if it's 24" or even 16" because the studs are on center, doesn't it leave measurements off for board, wool, or whatever you want to put in?

 

Yes 2 foot wide panel will screw up your wall which has to be either 24 or 16 inches on center.
Well doesn't have to be if you don't mind cutting and wasting a lot of gyp.
Unless you cover the wall with tongue and groove boards etc. and I would not want to be pounding in a bunch of nails into a 2X3 wall.

 

Nails? Was just planning on screwing it in to the masonry.
so for a 2' board, I have to make studs that are 26.5" OC?
With 5/8 gyproc that should be ok?

 

Maybe they say the board is 24" but it's not really.
like roxul 16" wool fits into 16"OC?

 

Screwing anything to the existing wall will radiate sound into your area.

I am not sure but it they spec it at 24 inches it should be 24 inches wide,
Otherwise what the H is the spec for!!!
Only way to tell is for you to check it with a tape.

 

Is this the material your referring too?

https://www.acoustimac.com/roxul-rb6...SABEgLsjvD_BwE


The stuff looks like it's more for sound absorption than sound deadening but might work.

I think a free standing wall not touching the existing wall would be better, you could also just use 6" thick rockwool or soft touch insulation.

I've got the soft touch in the ceiling of my basement for sound control and it;s fantastic stuff!

 

Hello. First off, there is no such thing as sound *proofing*. Only sound transmission LOSS measured in db. In your case, "decoupled mass" is your friend. However, structural sound transmission has many paths. Through floors, ceilings, pipes, ductwork etc.
You could build a wall, decoupled from the masonry by spacing it out from the masonry, insulate and sheath with two layers of 5/8" gypsum board, and the complete perimeter of the wall caulked. However, this may not solve your problem as I would guess you and your neighbor share a common structural floor and ceiling, to which you would have to fasten the wall framing to. Also you mentioned a basement. That alone tells me something as basements are notorious transmission paths. But it all depends on the type sound you are trying to reduce. Low frequencies especially, or impact sounds may be impossible to reduce. This is why real sound recording studios are built with rooms totally isolated from each other by use of floating floors, two leaf wall construction and many other techniques. Sound transmission in typical home construction may be impossible to stop, but building a wall as I suggested MAY reduce it enough to make it tolerable. Hope this helps.

 

Personally I don't think anybody really thinks there is any simple easy way to "soundproof" anything but we try to offer advice on ways to make improvements that offer the most bang for the buck!

 

Is cellulose any good or not as good as roxul?

 

I would expect cellulose, rockwool/roxul and soft touch to all be similar, they are relatively dense and heavy materials, unlike fiberglass, to absorb sound.

Only difference, cellulose does not come in batts so installing is different.

 

I seem to be seeing a NRC (noise reduction ( value of cellulose at 0.7 but roxul near 1.0.
maybe cellulose is cheaper and thicker since it could fill a joist bay entirely whereas roxul you need 2 layers