Rebuilding wall to neighboring unit

Posted: Sun Sep 23, 2007 3:51 am

Update: change in title, please see my new post a few posts down

Hello folks, long time no post.

I'll be moving to a new apartment soon, and the problem is that it's an older unit with a rather flimsy wall to my neighbor. From my side, it looks to be thin (3/16" or less) wood panels poorly nailed to some studs, with some kind of fibrous stuffing inside. (The fact that I can peek in thru the cracks shows how well this is put together) The panels resonate when I tap them with my fingernail. I can hear their TV fairly easily and their talking.

My question is if there is any hope of me building a reasonable, DIY, non-permanent false wall to block out some of this sound, and also to keep my system from blasting them back. I was thinking of something like getting some drywall sheets, and leaning them against the wall (with some padding to reduce vibration transmission) and then stuffing up the gaps as well as I could. Or maybe back the drywall sheets with acoustic cotton for more absorption. (I don't like to work with fiberglass because it gives me painful splinters)

This section of wall unfortunately has a sloped ceiling, so it's like a 8'x12' rectangle plus a triangle on top. I suppose I should seal this section too? Or is the lower section already helpful in deflecting the sound away (like a freeway noise barrier)?

I'm also open to other suggestions.

Posted: Mon Sep 24, 2007 5:03 am

find another place to live ? Wink

complain to the landlord about the noise and ask them to pay for it? then maybe putting up some rc over the existing wall and several layers of drywall might help. you'll want to do the entire wall and caulk everything to seal it. between the new drywall and existing wall put in a layer of r-11 unfaced insulation (compress it) to cut any resonances. if sound is coming through the ceiling, you may have to do something similar as well... but i'd get the landlord to sign off on it and hopefully pay for it... may be a code violation otherwise...

Posted: Tue Sep 25, 2007 4:38 am

Thanks for the reply. I agree that ideally the wall should be rebuilt, but I don't know yet if the landlord is ok with that, or how much it costs.

In the mean time, my plan is shaping out to be like this:

Take some MDF and make 4' x 4' squares out of those, backed with acoustic cotton. Somehow stack these against the wall, plugging up the gaps as much as possible. Some things I am not sure about is whether it is worth it getting thicker MDF (3/4" vs 1/2") and thicker insulation (R13 vs R19). I think in general "more is better", but in this kind of system I don't know where the point of diminishing returns is.

Posted: Tue Sep 25, 2007 6:44 pm

The poit of diminishing return is the beginning of what you are suggesting -

It isn't going to help you to any measurable extent - please don't throw your money away just because you feel the need to something............ it is not true that something is always better than nothing........

Rod

Posted: Tue Sep 25, 2007 10:34 pm

What are my options, then?

And what is the reason that building this other wall won't work?

Posted: Wed Sep 26, 2007 2:24 pm

the quick answer is any air leak is a sound leak. you need completely sealed mass to improve the TL of the wall assembly - which could be short circuited by whatever construction the wall already has...

other options? play your stuff quietly? talk to your neighbors and let them know you intend to play your stuff loudly and do they want to join the party? Wink

Posted: Sat Sep 29, 2007 4:28 pm

Update on my situation:

The landlord has agreed to have the wall drywalled.

So for now I need to do more research on this issue, but a couple questions come to mind for now:

As gullfo suggested, add RC, maybe better insulation, and seal as much as possible. I read an article about RC which talks about flexible caulk and making sure the drywall panels don't rest on any solid surfaces. Are there any more things I need to watch out for?

What's a good way to find a contractor that can do this work properly? Can any drywall installer do this, or do I need a specialty guy? Is this something I can even do myself?

I can have pictures and more diagrams later, but for now, there is about 150 total sq feet. Approx how much will it cost? (Located near San Francisco)

For now, let's assume that I don't get to also drywall the other side, so it's still thin wooden panels. Should I bother trying to make their panels heavier, e.g. gluing mlv on the other side?

Posted: Sat Sep 29, 2007 5:56 pm

a good drywall contractor should be able to handle it. 150sqft is about 5 sheets (32sqft each for 4'x8') plus some scrap. materials (drywall, rc, drywall paste (spackle), tape, drywall screws, caulk, paint, shims, etc...) are probably less than $250.

http://www.drywallinfo.com/

Posted: Sat Sep 29, 2007 9:14 pm

Quote:

so it's still thin wooden panels. Should I bother trying to make their panels heavier,

Try removing the paneling completely. If yer gonna drywall it anyway. You could [have] 2X4's ripped to install on the existing 2X4 wall stud making the stud cavities approx. 6 inches deep. Then insulate w R whatever size insulation goes on 2X6, and build out like Glenn suggested.

Posted: Sun Sep 30, 2007 2:57 pm

if you have the option to take out the panel (which is best), maybe its also possible to line the other wall with one or more layers of 5/8" drywall and caulk it. this will add mass to the other wall and seal it before putting in the insulation. the idea of ripping the 2x4 for an additional 2" is a good idea since you get the extra space (will isolate more) and can use R19 (not really going to isolate more). the RC on your side of the wall will be a big improvement, and if you put up more than 1 layer of drywall on your side it will help also...

Posted: Tue Oct 02, 2007 2:14 am

OK, here's a crude CAD drawing of the layout.
Blue is the floor on my side.
Brown is a single studded wall with only thin veneer wood panels nailed on.
1: has some insulation and wood panels on both sides, I assume. For now, let's assume that I'm not going to pop off the panels on the neighbor's side.
The right edge of wall 1 is 14 feet high (sloped ceiling) and the left side is 8 ft high.
4: this is the ceiling to the bedroom, which is about 8 ft high. All the walls below this ceiling appear to have drywall on the bedroom side. Above is attic, and I see exposed studs on all the walls.
3: cut-out for the bedroom closet. Wood panels on the left side, open studs inside the attic, drywall inside the closet.
2: potential source of noise leak. Open studs inside the attic.

For now the potential plan is to pop off all the wooden panels on my side of wall 1, put up drywall, and nail the panels back on. In my previous post regarding mlv, that was with respect to the back (stud) side of the panels on my neighbor's side of wall 1.
So for wall number 1, this can be drywalled with RC and whatever other goodies. I don't think I will resort to increasing the spacing by adding additional ripped (?) studs, as that will drive up the price significantly.

Q1: will adding a "better" insulation improve STC significantly?

Q2: What to do about wall 2, the potential noise leak? There isn't any insulation in the attic to help absorb sound. Should I:
a: pop off panel 3 and have them try to drywall wall 2 inside the attic?
b: just stuff some insulation between the studs of wall 2 and hope the attic acts like a big air space?
c: Confused

??

Keep in mind that I'm not aiming for a STC 60 wall or anything.

Posted: Tue Oct 02, 2007 3:36 pm

in place of mlv on the neighbors wall, add 5/8" drywall - no need to pop off the neighbors side, just lay it in there (supported with cleats and caulk and screws) then insulation then your interior layers of drywall on RC. insulation won't help you too much wrt isolation.

on the attic side, if you can add the drywall between the rafters or ceiing joists (check with a structural engineer to avoid things like collapsing ceilings and death or injury) which ever will give you the better seal, then insulation and interior drywall on RC.

you will then have some reasonable isolation - remembering that air leaks or hard contact between walls can significantly reduce the TL...

Posted: Tue Oct 02, 2007 5:00 pm

Quote:

2: potential source of noise leak. Open studs inside the attic.

You will be doing yourself a favor to insulate this area. Sure, you will be doing the landlord a favor as well...but the heat buildup alone in the attic that creeps into your bedroom and into the upper area of the living room could be regained in lower power bills. Over time:)

And it will help to reduce the transfer of sound entering/leaving the living room.

Posted: Tue Oct 02, 2007 7:01 pm

gullfo wrote:

in place of mlv on the neighbors wall, add 5/8" drywall - no need to pop off the neighbors side, just lay it in there (supported with cleats and caulk and screws)

Do you mean cut drywall into tall, 15" wide strips and fit them in between the studs, and then seal all the gaps? I think this would help, although it sounds like it will more than double the labor cost. I'm still waiting to get my quote for the drywall job, but for now, I'm going to propose a payment scheme where the landlord pays for a "regular" drywall job, and I pay for all the extra, e.g. RC, acoustic sealant, etc. So I'd like to keep my end of the cost below a few hundred dollars. Also, won't this scheme create the dreaded "3 leaf system"?

Quote:

then insulation then your interior layers of drywall on RC. insulation won't help you too much wrt isolation.

I did some more reading last night, and it seems like the type or density of insulation won't make much of a difference. However, in my case, it's purpose would be to damp the vibrations of the neighbor's panels. I think the current insulation I have is too light or fluffy to do that.

Quote:

on the attic side, if you can add the drywall between the rafters or ceiing joists (check with a structural engineer to avoid things like collapsing ceilings and death or injury) which ever will give you the better seal, then insulation and interior drywall on RC.
you will then have some reasonable isolation - remembering that air leaks or hard contact between walls can significantly reduce the TL...

I think it will make the best seal to drywall the triangle labelled "2", but I will wait to see how much extra it costs. The drywall guy suggested to not bother with RC in this area. I was also considering just stuffing acoustic cotton between the studs, without adding drywall. It seems like the acoustic cotton blocks have a reasonable STC rating all by themselves.

I'm not sure yet exactly how the studs or panels are laid out, so I don't know if the "hard wall contact" with wall 3 will be a problem or not.

Posted: Wed Oct 03, 2007 8:38 pm

the additional drywall against your neighbors walls (between the studs) won't add a leaf because its up against it... use r13 insulation - should be fine.
use the same construct on #2 as elsewhere. the cotton blocks won't really do anything to isolate...

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