Row house shared floor joists impact noise

[csblues]

I live in a end unit two-story row house (built in 1900), on which I've done quite a bit of soundproofing work, mostly adding drywall and green glue to the old brick and plaster party wall, with pretty impressive results.  Now I'm trying to resolve an impact noise issue.  Every time my next-door neighbors walk on their hardwood floors, the floor in my kitchen shakes.  The key issue is shared floor joists--theirs come through my walls and overlap up against mine for about ten inches (I can see this in the basement and assume it to also be the case below the upstairs floor).

I don't think it's possible to separate these joists.  Is there a way to reinforce them or put some sort of absorbing trusses between them?  Would Rockwool or some other fiber dampener under the floor have any effect?

Other suggestions? Many thanks.

[Randy S]

Insulation will not work and most likely adding truss will just create more pathways for the problem to travel. I think a better approach would be to use green glue (3 tube formula) and hardy backer(cement board) to the underside of the substraite screwed to the existing OSB. At least it will absorb some of the vibration transmission.

[csblues]

Thanks much!  I will get some hardibacker and give that a try.  I wonder whether putting up a 2 x 4 frame along the side of the basement wall from floor to ceiling would also absorb vibration?

[Randy S]

Hard connections and rigid framing will not reduce vibration. Seperating the two units is what needs to happen but thats not going to be possible in your case.