Remove plaster for soundproof?
I’ve got a brick party wall with plaster applied directly to it, and it’s a sieve for noise. It is likely to have missing bricks from past intrusions, old gas lamp lines, etc. I’d like to remove all the plaster, fix the brick underneath it by replacing missing bricks and repointing, insulate the joist pockets with rockwool, and then cover back up with mass loaded vinyl, rockwool over that, and a quietrock wall in front.
The only problem, none of the soundproofing guys I’ve talked to are interested in the remedial work and only want to do the easy job of adding new material. I couldn’t bear the thought of investing money into this wall without fixing the source problem. Who should I call to get this done?
colonialrevival
in General Discussion 4 years ago
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28 replies
colonialrevival | 4 years ago
I appreciate all of your thoughtful comments. They’ve helped remind me that I should add — the neighbors have intact plaster on the same wall. The wall is plaster applied directly to brick. There has been chasing into it on both sides for power outlets, etc, over a number of years I’m sure. There were once gas lamps in the room and those lines are no longer in use, but I’m certain there’s a gas pipe behind. There are large sections of the wall that I can knock on and the wall sounds hollow, but nothing predictable that would indicate a wooden partition to close up a past passageway or something.
As the brick is only 2 wythes thick, I’m guessing our joist pockets go all the way through and sound can travel that way. While I hear you all on not going exploring in the plaster, would it be beneficial, still, to pull back some floorboards and insulate there? Moreso than just pulling off the baseboard and spraying expanding foam beneath?
Guest User | 4 years ago
It depends on what’s behind the plaster. I have plaster on brick and can hear the neighbors in areas. In other areas it appears my walls are built out. If the plaster is directly on the brick, then it may not be worth it to go on an expedition. Easier to add like Urbandad and JH are suggesting. As mentioned above, plaster itself is a good insulator. Can you open an area and see what’s behind or did you do that already?
Guest User | 4 years ago
Definitely need to isolate the vibrations. In gut construction we have staggered two insulated walls on neoprene separators, not unlike mounting HVAC on a concrete pad. The plaster in itself is a good sound insulator.
Sound is tricky. I once lived in a 1920s building with gypsum plaster walls. The only places where you could hear the neighbors was where they had done a hot water riser replacement – I could hear the couple next door arguing in their kitchen if I opened our tiny pantry and inexplicable the interminable playing of The Girl from Ipanema was only noticeable under water in the tub!
JohnHancock | 4 years ago
Perhaps the neighbors have the plaster removed, in general I think the plaster is a decent solid layer. I would build upon that. Sound is vibrations so to stop sound traveling you have to “float” things like in a recording studio where you separate layers.
This is not really possible in a residential space but we do the best we can.
Guest User | 4 years ago
No disrespect to those who clearly know more. If it were up to me I would do exactly what you you want to do. I agree with urbandad that it is more costly, difficult and messy. 9/10 people you call will tell you to do it the faster way. They probably don’t want you to waste your money and live through this. In my experience people would want it done the faster way because the alternative will be more expensive. Talk to a few more people then decide. Good luck!
colonialrevival | 4 years ago
After sitting with it, I’m not sure I concur with your analysis — we can clearly hear the words to every conversation between our neighbors. Are you certain that stripping plaster and repointing is a waste of time?
colonialrevival | 4 years ago
Thanks Urbandad.
FWIW, our party wall is only 2 brick wythes thick.
Curious about the joist pockets, though, as the sound does also come through the floor. Basically, I’m incredibly nervous about investing time/energy/$$$ most of all into something that will still have potential pitfalls or variables left unchecked. Should I have my soundproof guys pull the floor/subfloor up and throw some insulation there? Can’t do it from below as there is decorative moulding.
hkapstein | 4 years ago
If you’re going to build a new wall in front of the old wall, you may was well just just leave the plaster and invest your efforts in decoupling and adding layers. The party wall is quite thick anyway, and parts of it are controlled by the neighbors and you won’t be able to do anything about the defects on their side, and it’s unlikely that this will make a big difference anyway. The plaster removal and masonry work will be a messy, costly, and difficult job, and you likely won’t find the smoking gun you’re looking for, and you’ll wish you hadn’t done it IMHO.