Re: How to soundproof shared walls and floors/ceilings
From: James Kacki (
Date: Mon, 28 Jan 2008 08:36:31 -0800 (PST)
Also, resilient channels (+/- 1/2" metal spacers) to keep the drywall away from the studs, prevents sound from vibrating through the drywall & studs. In Canada (not sure about the U.S.) it's a Code accepted means of achieving a higher STC rating (Sound Transmission Coefficient). Also, acoustic sealant under the sill plate of walls or anywhere else where a sliver of an opening could occur from one side of the wall to another.

On 28-Jan-08, at 10:04 AM, Laura Fitch wrote:

Use dense-pack cellulose insulation in the party wall. It is much more
effective at sound dampening than regular acoustic insulation.

Laura Fitch, AIA, LEED
Kraus-Fitch Architects, Inc
110 Pulpit Hill Rd.
Amherst, MA  01002
lfitch [at]

-----Original Message-----
From: Bob Morrison [mailto:RHmorrison [at]]
Sent: Monday, January 28, 2008 9:28 AM
To: cohousing-L [at]
Subject: [C-L]_ How to soundproof shared walls and floors/ceilings

    On Jan. 27, Sharon Villines wrote:

I would like to hear from the construction wise among us who know how to create shared walls, floors, and ceilings so sound does not penetrate. [end

  I am not an expert on construction, but:

The best way to prevent noise from carrying thru shared walls is to put lots of insulation in the walls and use offset studs. That is, put a set of studs in the half of the wall that is facing one unit and put in another set
of studs, offset from the first set, in the other half of the wall.

In a building that has four or more units per floor, I recommend having concrete floors. However, there is a problem: You must put a "chase" thru the floor to run water, sewer, and (if applicable) gas and FHW heat pipes to the units. This isn't a problem in a large building because you can spread the cost of the chase over many units. If you have fewer than four units per floor, the cost per unit of the chase may be prohibitive, and that may make
concrete floors impractical.

Whether you have wood or concrete floors, I recommend you have a rule that all units that have another unit underneath must have (and keep in place) wall-to-wall carpet on all floors except in the kitchen and bath. You get a
lot more noise in the units below if the floors are hard-surfaced.

I know there is more you can do to soundproof floors, but I don't know

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