Expert: Ted Barnhill (Principal, Design45 LLC) - 11/12/2008

Question
I am renovating a 100 year old house into 3 suites.  What is the best way to sound proof between floors and walls?

Answer
Linda,

There are many wall and floor constructions that are "STC rated" for various levels of noise reduction.

The least expensive solution is batt insulation, which does a good job of mitigating high-frequency noise.  Spray foam insulations, while more costly, do a better job still.

Lower frequencies (bass speakers thumping) require either a massive wall or more creative construction.  Adding a layers of drywall helps at modest cost; better yet is drywall on spacers (Z-shaped steel channels).  In new construction or major remodels, common techniques include using masonry walls, concrete floors, or double/offset stud walls.  A basic primer can be found at http://www.stcratings.com/  

I hope this helps.  If you have any specific follow-up questions, feel free to post them.  -Ted