Sound transmission disaster, now what?
This feels like a disaster to us, at least. As part of a very extensive remodel, we're adding an in-law unit with the idea of renting it out to pay for a significant portion of the remodeling loans. (Everything is being done legally and by professionals.)
From day 1, we emphasized to our architect and contractors that sound separation between the units, which share a wall, was critical. However, there is no wording about this in the construction contracts. Although we are building neophytes, we thought our concerns had been adequately addressed -- for example, a second interior wall was built to separate the units, we understand the walls are all very well insulation, and (per city code for multi-unit structures), there is a one-hour firewall between the two parts of the building, all the way up through the attic to the roof.
But we had no way to test the effectiveness of the sound insulation until now, when the sheetrock is up, the cabinets are in, and the doors and double-pane windows have been installed. We are, or should be, very near the end of the project.
Our test was a disaster. From either unit, music played loudly in the other unit was perfectly audible. Even at likely "normal" listening levels, a radio played in the living room of the main house came through clearly in the bedroom of the in-law unit. We imagine conversations will come through the same way. It feels like there was no special sound blocking done at all. This is exactly what we were trying to avoid.
What now? We plan to call a meeting with the architect and builders, but what can be done at this late date? The in-law unit is too small to add anything to the walls on that side, but could we put something up in the house to mitigate the problem? Not something ugly, though, because it would be in our living room!
I am just at a loss and wondering what we can possibly do now. I would like to have some suggestions to make when we meet.