Building codes have never created the demand that noise reduction construction types be incorporated into architect's concerns.
Many condo, tenements and townhouses have neighbors who don't want to hear their neighbors- either through walls(echo transmission)
or ceilings that involve footsteps which is best classified as (mechanical transmission).
We have the highest rated reviews at http://www.njsprayfoaminsulation.com because we inject foam into the walls that solidifies
like a lightweight but dense sponge of foam that expands immediately sealing every unseen crack, seam or nail hole .
This has the soundproofing companies scratching their heads while saying it can't be done!
If you know how to make good foam, the rules change. We can't change the past construction, but we can offer the
absolute best change in Brooklyn, Manhattan, Staten Island, Hoboken, and Jersey City in NJ
See our soundproofing page for more.... http://www.njsprayfoaminsulation.com/our-services/soundproofing/