Author Topic: soundproofing lath and plaster wood stud wall  (Read 9905 times)

lathandplaster

  • Guest
soundproofing lath and plaster wood stud wall
« on: November 22, 2010, 07:18:05 PM »
I have noise coming through a wall that is lath and plaster over wood studs. The noise is largely people's voices and a dog barking in the adjacent unit. (There is also the issue of creaky floor joists when they walk, but I understand this may not be fixable).

What is my best option for soundproofing this wall? I don't want to remove the lath and plaster, and when I spoke to the person at QuietRock, he told me this product would not work on a lath and plaster wall. Thanks.

Randy S

  • Senior Soundproofing Technical Specialist
  • Global Moderator
  • *****
  • Posts: 790
    • Super Soundproofing Co
Re: soundproofing lath and plaster wood stud wall
« Reply #1 on: November 30, 2010, 11:00:05 PM »
You can add a layer of our MLV w/psa directly to the lath and plaster wall followed by a new layer of 5/8" sheet rock with green glue sandwiched in between (3 tube per 4'x 8' sheet)
Screw the drywall directly to the studs.
Now this is not the best system that can be done, we view this system as a band-aid approach.If you want to achieve better results than you would need to remove the lath and plaster and float the new drywall on clips and channel.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

lathandplaster

  • Guest
Re: soundproofing lath and plaster wood stud wall
« Reply #2 on: December 02, 2010, 10:30:36 PM »
Thanks, Randy. What if I build a new frame starting an inch or two out in front of the existing wall, and put QuietRock or double gyprock on the new frame, with insulation in the new cavity and acoustic seal around, etc?

This is creating a triple leaf, but if I have about 5 or 6 inches between the old wall surface and the new one, is the cavity deep enough to reduce any problem at lower frequencies? Most data I have seen refers to a tiny air cavity, as in attaching RC to and existing wall, creating a cavity of less than an inch.

An alternative would be to punch holes in the lath and plaster or to remove it entirely. I'd prefer to avoid this in terms of mess and the worry that I'm losing a lot of existing mass. I haven't seen any useful data on triple leaf in terms of how the effect diminishes or the resonance lowers as the air cavity gets deeper, or as the mass applied to a new wall becomes greater. Any ideas? Thanks again.

Randy S

  • Senior Soundproofing Technical Specialist
  • Global Moderator
  • *****
  • Posts: 790
    • Super Soundproofing Co
Re: soundproofing lath and plaster wood stud wall
« Reply #3 on: December 02, 2010, 11:46:18 PM »
Doing the triple leaf system in any format usually only changes the frequencies that are expedited throught the current assembly. I dont think I would take the risk, remove the lath and plaster. Add the mass to the final layer or decouple from the existing wall with clips and channel.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

johnbergstromslc

  • Guest
Re: soundproofing lath and plaster wood stud wall
« Reply #4 on: December 03, 2010, 04:04:11 PM »
Your plan to build an additional wall to decouple the noise is a good one, but you don't have to go that far to get good results.

I agree with Randy, you absolutely should remove the old lath and plaster.  Besides having an open stud cavity and being able to get some insulation in there before drywalling, you can see any defects in your neighbors plaster that need fixing/sealing, i.e. penetrations, 'leaky' electrical boxes, etc.  

Instead of a double stud wall eating up 5-6" of floor space, I suggest a staggered stud wall.  After you've torn off the old lath and plaster, increase the width of the top and bottom wall plates, corners and door/window jambs with a 1x2 furring strip - this will add only 3/4" to the thickness of your wall.  (This is the minimum, but you can add 2x2's if you wish, for a 1.5" thicker wall.  A 2x3 would add 2.5", but that's probably overkill.)

johnbergstromslc

  • Guest
Re: soundproofing lath and plaster wood stud wall
« Reply #5 on: December 03, 2010, 04:08:14 PM »
Then add the extra studs on your side of the wall, reposition any electrical boxes, insulate, add double 5/8" drywall and seal the wall very well.  If you want to put MLV between the drywall panels, that will help even more.

It seems like a lot of work, but it's really what you'd be facing by adding an additional wall, anyway.  You shouldn't be afraid of demolition - that part is a snap.  Just make sure you have authorization from the landlord/HOA before you proceed...

A staggered stud wall with insulation and double 5/8" drywall rates an STC of 58, and MLV would probably add a few points.  But since you neighbor's side won't be as good, you'll end up lower than that.  STC 50 is a reasonable expectation. 

lathandplaster

  • Guest
Re: soundproofing lath and plaster wood stud wall
« Reply #6 on: December 03, 2010, 08:37:31 PM »
Thanks for your help, Randy and John. You have convinced me to remove the lath and plaster. I'll let you know how it turns out in a couple of weeks.