There is a private house 2 floors of aerated concrete with a cold attic.
— Attic floor: joists 50 x 150 mm with a spacing of 60 cm, inside the joists hermetically placed foam 10cm.
— roof – soft roof on the boards + 5 cm of rock wool inserted between the rafters of the roof.
— everywhere on the 2nd floor installed stretch ceilings and light fixtures. From the loft floor joists to the suspended ceiling – about 7-8 cm.
Naturally, the lack of a sound reflective layer is unacceptable: you can hear everything from one room through the attic from another room, etc. But the most annoying is the outside noise – the barking of dogs. But here most of the noise seems to come through the windows.
On the basis of all this I plan to do for the beginning 2 overlapping steps:
a. improving the sound insulation of the attic floor
b. improve the thermal insulation of the attic floor
Thermal insulation – I plan to screw transverse boards on the beams attic floor above and put on top of 2 layers of absorbent cotton 5 cm (insulation). Styrofoam will remain as well.
Soundproofing. It is clear that you need to add a sheet of material. Also note that lowering the ceiling below the current level is unacceptable (already too low).
The easiest option – remove the suspended ceilings, screw to the bottom of the joists 2 layers of gypsum plasterboard, lay fiberglass fleece, cover with silicone joints, etc. Then return the stretch ceilings in place. The next option – a one-level ceiling on the vibratory hangers (GFB + GPB + rockwool ultra-thin layer of wool) – i.e. 6 – 7 cm from the floor joists.
1. How critical for sound insulation that the foam will be left between the joists?
2. Given that the main problem – barking dogs – is limited in the solution due to the weak link, which are the windows.
And for windows, achieving insulation greater than 30 to 35 dB (and thus the entire wall) is problematic. Does it make sense to prefer a simple option (just lining 2 sheets of plasterboard)? Or still choose a more complex and expensive option with vibration hangers?
In your case you don't need any vibratory hangers.
Gypsum fiber + gypsum plasterboard + rock wool. The foam is better under the roof, and the wool between the beams.