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May 1, 2008
Party wall soundproofing
I searched the forum and found a few posts on party wall soundproofing, but I'm looking for more specific advice, and I would really like to hear from people who did this.
After we moved into our house, we realized that one of our party walls sounded surprisingly thin. We can hear music, TV, conversations, vacuum cleaner, etc. The neighbors are not particularly loud, and what we can hear appears to be a fairly normal noise level (and they can probably hear us). The wall is brick covered by the original plaster. I was surprised that brick and plaster could transmit so much noise, but it does. I've read on soundproofing and I'm getting familiar with the basic concepts (mass and standoff) and with the materials. But the more I read, the more I realize that there is no easy and perfect solution.
I'd like to hear from people who soundproofed their party walls. What did you use and what results did you get?
And where in Brooklyn or NYC can I find soundprooking materials? I was at Lowes and Home Depot recently. When I asked them about soundproofing materials they only had Homasote 440. They had never heard of Quietrock and Green Glue. I was suprised since I thought these thing would be in high demand in NYC.
thanks in advance!
Comments
We too were so surprised to learn this about the party walls between some Brooklyn brownstones. Brick and plaster do nothing to block noise. You go from an apartment to a house and think you're going to be king of your domain and not have noise issues as before but voila, it's the same. Maybe because the houses were built rapidly at the turn of the century and would be constructed 2 or 3 together at the same time.
There is little you can do to actually truly soundproof. I'm sure you could find someone who would charge you a lot of money to do some stuff on your side of the wall, but it wouldn't be very effective. To really soundproof your space you'd have to completely remove your walls and install soundproofing that allows no cracks or space for sound to travel through.
Posted by: guest at May 1, 2008 1:55 PM
We did a lot to soundrpoof our walls by:
1. Building a wall that stands off the party wall (important, it can't touch the party wall)
2. Batts of cotton soundproofing insulation between studs
3. 2 layers 5/8 sheetrock
4. Caulk/tape seams thoroughly!
Posted by: guest at May 1, 2008 2:51 PM
Thanks 2:51, that's very similar to what I'm planning. I agree that the space between the party wall and the new wall is probably the most important aspect. What cotton soundproofing insulation did you use, and where did you get it? Are you happy with the results?
Posted by: Ibis at May 1, 2008 3:01 PM
"Brick and plaster do nothing to block noise"
That statement is simply untrue. The inherent mass of brick and plaster means that a wall comprising these materials has an extremely good STC (sound transmission class) rating, especially compared to a drywall partition not specifically designed to attenuate sound. The only type of sound a masonry partition is not particularly effective in stopping in its tracks is impact, as opposed to airborne, sound. If your masonry/plaster party wall is allowing the passage of moderate sound sources, it probably has holes or cracks in it somewhere.
A question to the OP: is the plaster applied directly to the brick or is it applied over lath (which would, I think, be rather unusual)? If the former, and if it's original with no significant cracks (which cracks would reflect cracks in the brickwork too), then I would be totally flummoxed as to how you can hear conversations from the other side. If the latter, however, it is conceivable that there are cracks in the masonry that have not telegraphed their presence through the lath and plaster.
Posted by: johnife at May 1, 2008 3:01 PM
Johnife, I can hear right through my plastered masonry wall... and I have a really nice old lady living next to me. I think it's the gap between the wall and the wainscotting.
Posted by: guest at May 1, 2008 3:10 PM
It is plaster applied directly on brick (no lath). The plaster has no visible cracks. The two houses are identical and were probably built at the same time. I suspect that the brick party wall was poorly built and may have some crack or holes. Another interesting observation: When I'm in the cellar, I can hear our neighbors washer and dryer quite well, and recently I realized that the noise is coming through one of the joist pocket in the brick wall just above the foundation.
The house on the other side is a different house, and we hear absolutely nothing through that other party wall.
Thanks for the reponse Johnife, and if you have any suggestion on how we could investigate and fix this, please let me know.
Posted by: Ibis at May 1, 2008 3:16 PM
Okay, Ibis, your 3:16 comment explains a lot. I suspect your house and the identical one next door were built together with a single wythe (one brick, or 4" thick) party wall. The shallowness of such a wall would necessitate the ends of the floor joists to penetrate all the way through it (they need at least 4" of bearing) assuming that joist hangers (which I don't think were used much 'til beyond the '40s or so) were not used. The sound is probably passing through whatever gaps there are between the brickwork and the joists. This, of course, would mean that putting a second, insulated, drywall wall extending between your floor and your ceiling would do next to nothing to solve your problem. The sounds will still be passing through the joist/brick gaps, into the space between your ceiling and floor, and up through your floorboards or down through your ceiling. Whatever secondary soundproofing layer you chose will require the removal and later replacement of a swath of ceiling along the party wall line to allow the sound attenuation to smother the joist area.
The fact that the house on the other side of you is different almost certainly means that it has its own party wall. thus, between you and it there is at least 8" or so of masonry with the certainty that there are no joist penetrations between you and it.
Incidentally, I don't want to unduly alarm you, but if sound can pass so easily through that masonry wall, fire could too, especially if my premise that there are wood joists passing through it is correct. When were the houses built. These days, for sure, such a wall would have to be 2 hour fire rated with fire-stopping material at its interfaces with other portions of the building.
Posted by: johnife at May 1, 2008 3:40 PM
as long as you don't expect soundproofing to work miracles (total absolute sound isolation) you can do a lot. Marjam contractor's supply in east williamsburg carries quietrock and if money is no object their best stuff can be amazingly effective at muffling unwanted sound.
Posted by: Jimmy Legs at May 1, 2008 3:57 PM
"The sounds will still be passing through the joist/brick gaps, into the space between your ceiling and floor, and up through your floorboards or down through your ceiling. Whatever secondary soundproofing layer you chose will require the removal and later replacement of a swath of ceiling along the party wall line to allow the sound attenuation to smother the joist area."
This is true--start by insulating/caulking these spaces and see if you get a reduction in sound. You should hear at least a small difference.
Posted by: guest at May 1, 2008 4:01 PM
anyone know how much it costs to hire a soundproofer to do green glue (in one room)? i contacted one who quoted me $500 for the consult, which made me think that a full soundproofing would be really expensive. i'm only looking to do one bedroom wall and a boiler room vent.
i guess i deserve neighbors with screaming babies, since i live in park slope...
Posted by: guest at May 1, 2008 4:14 PM
Thanks Jonhife, you confirmed what I was thinking about the way the houses were built. And yes, I was thinking that the party wall is probably not fireproof since I realized that there are holes in the wall at the joists.
These are 3 story brick houses in Bed-Stuy, build in 1899 according to city records.
Is this common in Brooklyn?
Posted by: Ibis at May 1, 2008 4:15 PM
"Built in 1899" really means "1899 or prior"; there was a large fire that year which destroyed thousand of City records.
I have no idea whether the single wythe party wall scenario was common in Brooklyn for adjacent identical houses. Similarly to you, the house one side of mine is identical and the house the other side is different. I haven't been in a position to, or had the need to, ascertain how thick the wall is between my house and the identical one, but I do know that sound transmission has never been a problem (if it was, I'm sure I be told, 'cause I sometimes let my music really blast).
Posted by: johnife at May 1, 2008 4:31 PM
We have the exact situation in our brick row house. We can not hear normal conversations at all but can hear music. They recently refinished their floors and the smell filled our entire house as well. The masonry joist pockets are the entry point.
Posted by: guest at May 1, 2008 6:13 PM
quietrock is great. and that green glue is good too. you should be able to put both up yourself.
Posted by: guest at May 1, 2008 7:04 PM
conversations like these are why I read Brownstoner. Thank you everyone for an informative and civil thread!
Posted by: guest at May 2, 2008 2:05 PM
I am the last house of a row of houses (a brownstone). All built by or before 1899. In the 1930’s a brick apartment building was built next to me.
When I play music loud… I sometimes get a knock on my door from the woman who says her apartment wall hits against my parlor floor. I use to have a very high end stereo and never got any complaints. Then it broke… now I have this crappy sony all in one system.
It seemed to me like even though the other stereo was louder… somehow she never heard it?
I very rarely hear anything… I want to say never… except that sometimes on the garden floor that buts up against an exterior semi enclosed passage… I here noises… the very simple noise of just someone walking through the take their trash out.
So it’s weird… because there is either no sound whatsoever between the buildings…. Or in strange spots… sound like it is just right there??
Posted by: guest at May 2, 2008 2:33 PM
A friend of mine had a similar noise complaint in his party wall. He built a wall in front of the problem wall and had an insulation contractor spray a closed cell polyurethane spray foam into the new wall and he says he can't hear a thing thru the wall since the foam was installed.
Posted by: BMarch267 at May 3, 2008 6:06 PM
closed cell spray-in foam is GREAT for deadening sound. not as great for impact noise however, but that's probably not the issue here.
Posted by: guest at May 3, 2008 8:42 PM
So many answers to questions can be found by reading an old Journal for Light Construction article that can be found at http://www.soundsense.com/pdfs/Schnitta-JLC-0206.pdf.
For example -
1. Insulation does not stop sound, it absorbs, BUT blow in insulation will fill holes. This is important since a 1" hole will negate most of whatever soundproofing you have performed.
2. The one inch hole is why Quiet Rock fails. This article mentions an alternate product, SoundSense LV-1. This product is like 3+ layers of sheetrock.
3. The best party wall would be the previously described double wall with SoundSense LV-1, or NoiseOut 2 (when there is amplified sound). If there is not enough space for the double wall, the clips described in the article with LV-1 or NoiseOut 2 will work equally well.
4. Make certain any electrical outlet is acoustically wrapped.
5. Caulking is critical (remember the 1" hole).
6. See the article for additional help.
This product was also highlighted in an article by Myron Ferguson ("That Drywall Guy") in Fine Homebuilding.
Posted by: guest at May 4, 2008 12:09 AM
Good info, 12:09. We might soundproof a wall in our house that way eventually, but sadly it's the smallest bedroom in the house so we'd lose another 6 inches of width in the room.
2:33 we have a loud music issue next door and in trying to work with the homeowner we learned that his house had very little rugs anywhere, and his speakers were sitting either directly on the floors or were in a boombox on a piece of furniture that was sending the sound directly into the floor. As some are describing, the noise is traveling between shared joists in the floors and the back wall of our houses.
Try putting a rug and sound absorbing pad underneath the shelf or table you have your stereo unit sitting on. And don't rest that piece of furniture directly against the wall. Ask your neighbor how it sounds then. You should get on the phone with her one day and start moving things around in your space, asking her what she hears or doesn't hear. See if that helps things. If you can find a way to listen to your music at the volume you like that she finds more tolerable that makes both of you happy.
Posted by: guest at May 4, 2008 9:15 AM
A few comments from above:
#1 if you hear sound through a wall, this does NOT mean fire can come through. The block wall, and other concrete partitions, are resonating in the vocal sound range. This is not due to holes in the block.
#2 Standard cheap fiberglass will work as well as anything. Cotton is very expensive, and cellulose does not work any better. Foam is the worst. Look at the dozens of tests done by the NRC in Canada. The finest acoustics lab in North America. Clearly demonstrated that cheap fiberglass was as good as it gets.
#3 Building a small wall in front of the block wall is an excellent idea. Use 2x4 wood or steel studs, or even 2x3 steel. Just don't have the studs contact the existing wall. This is "decoupling" the new wall from the old wall.
#4 Installing these things, including the green glue that was mentioned, can be done by a drywaller or handyman.
Posted by: guest at May 7, 2008 10:32 AM
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