soundproofing between stories/apts - ceiling and floor cavity

[Marcia Langley]

What successes has anyone had in soundproofing an old building between stories (which are different apts) please? we are in between 2 tenants: we have unit 2 and live bwt our tenant apt 1 and tenant apt 3. Our kitchen has an original t&G wood ceiling, and the tenant BR above has wideplank floors - can hear all - seems there is zero insulation between our ceil and top BR floor... and we are moving to our next multi purchase in a month and need to soundproof to keep our great tenant upstairs and want to attract and keep a good tenant in our apt 2 where we are now... all i see are ads for 2 layers of 5/8" sheetrock with rubber clips between...wonder if there is a DIY blow-in we can use in that cavity between his floor and our kitchen ceiling? Although that may wreck our original T&G wood ceiling...

Also in our BR, top apt. kitchen is above...so we have the situation where we feel we cant use our kitchen after 11ish even if we want to...and where we may be awakened by movement in the upstairs kitchen when we sleep in...hoping for a reasonable and reliable solution...so this triplex is not functionally useless due to lack of basic sound proofing

[Greg M.]

I had a similar issue where every time someone walked on the floor in the top unit, it was like drums in the unit below. You could hear conversations, running water, everything. I don't believe that you will have any success with blowing in insulation. I was told it will not address the main problem which is likely the sub-floor boards have come loose or warped and the joists have become loose and every time someone walks they rub against each other. 

I was proposed two solutions. First was ripping up the entire floor and sub-floor and likely concrete and then securing the joists. The other (which I went with) was to remove the floor in the top unit, replace any damaged sub-floor and have the entire sub-floor re-screwed down. A layer of concrete was poured on top of the sub-floor. The thickest/highest end foam sound insulation was laid and then new tile flooring was installed on to of it. 

This hasn't stopped the noise completely, but it has reduced it greatly. I'd say there has been a 95% reduction in the sound transfer.