For various reasons, we are considering adding soundproofing to the walls and ceiling in our apartment (just newly built with a concrete frame).
The wall already has soundproofing against the concrete wall, presumably an air gap, 45 mm metal stud with 45 mm mineral wool, and then a layer of drywall. Is there any point in adding an extra layer of drywall, making it a total of two layers? How much improvement in dB would this provide?
For the concrete ceiling, we are thinking of suspending a ceiling with mineral wool and drywall. The problem is that a window is placed close to the ceiling, so the space is a maximum of 70 mm. Our idea is a 10 mm air gap, 45 mm metal stud with 45 mm mineral wool, and then 13 mm drywall, which with filler and paint should give exactly 70 mm. How much sound reduction in dB can we expect with such a wall?
