Garmaine Staff asked 2 years ago

I’m building a soundproof room in a garage for a friend, after having done something similar for myself, but am not sure about the ceiling. I was planning to use two layers of acoustic plasterboard (roughly 40kg per 2.4×1.2m), with rock wool in between the joists. The joists in the garage look like this:


Would that be too much mass for the joists, or would it be okay?