The makeup of the rowhouse project, with upstairs and downstairs units, is a strong candidate for advanced sound reduction techniques. The challenge with wood frame buildings, as we typically build today, is that they are excellent at transmitting sound and vibration, especially through the floor.
As the project owner/builder/person in charge of everything, I have to make the decision on what additional materials are worth the investment to reduce sound. To me, significant expenditure is justifiable here, because sound transmission through the floor is particularly annoying. A noisy building could lead to a reduction in satisfaction of the residents, higher turnover, conflict and complaints to management (i.e me), etc.
It is hard to quantify a certain amount of sound reduction, measured by STC rating, for a given amount of money spent. Despite the lack of certainty, I am going to go ahead and invest where I have come to believe, after my research, major improvement can be made. I believe the biggest issue will be footsteps, or banging, music, and conversation from those living in the upper unit, which happens to be located above the bedroom of the lower unit. Impact noise I have come to believe cannot be mitigated without some different ceiling assembly and products than are conventionally used.
The primary technique I am going to deploy is a rubber clip that is used to attach the drywall to the ceiling. By disconnecting the drywall from the structure, impact noise will be dampened, I am also going to use a green glue gell product that is spread in between the double ceiling drywall sheets (both type x 5/8 drywall).
these are the rubber clips that fasten to the ceiling. A drywall hat channel goes in next, and then drywall screws on to that. It replaces another product, the drywall sound bar, that is more inclined to fail or be short circuited.
This is the total assembly of the ceiling of the lower unit, with some minor difference. Firstly, we don't have open web joists, we have the closed style. These are likely noisier than open web joists. Secondly, we are going to use the green glue sound damping product between the two layers of drywall, this should add some further STC value. We don't know exactly what, because this assembly has not been modelled by the consultant that published this work.