[Cob] Soundproofing on a traditionally built wall

[Raduazo at aol.com]

I do not know if this would help, but I just did a cob wall over bamboo lath. 
Bamboo was split with a conventional 5-way splitter and applied to a 
conventional stud wall using "horse shoe nails." (That is the U-shaped nails sometimes 
used for attaching fabric or wire to a wall.)
    This was then covered with a layer of cob pushed through the openings in 
the lath, followed by a layer of straw/clay plaster, a layer of horse 
manure/clay plaster and a final lime plaster.
    The resulting wall is much more massive than a conventional drywall 
surface. I think it is important that the inner layer of the wall has a different 
harmonic frequency than the outer wall. Plus I have conventional insulation 
between the walls.
    I did not do enough of this to determine if it was of any acoustical 
significance, but it should cut sound, and the wall cost less than $1.00 since the 
bamboo, the clay, the straw and the sand were all free. I am still on my 
first bag of lime for a 10 x 9 foot cob wall and a 3 x 9 foot bamboo lath. The 
store bought lime is the only ingredient that cost money.
Ed