Spent €2,000 on a sound-insulated ceiling, but I can still hear my upstairs neighbours. What went wrong?
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I recently bought an apartment where I can hear the upstairs neighbours talking and walking. The impact noise is quite loud, while their voices are mostly muffled. After months of research, I decided to renovate one 9 m² room so I would at least have somewhere quiet to go when the noise became overwhelming.
I hired a contractor to install a self-supporting acoustic ceiling. The construction consists of:
-A self-supporting metal frame fixed to the surrounding walls, not suspended from the concrete ceiling
-Approximately 7 cm of empty space between the concrete slab and the metal frame
-Isolation tape between the perimeter metal profiles and the walls
-Knauf acoustifit, 8cm thick
-Two layers of 15 mm fire-rated plasterboard
-Caulk around the perimeter and on every seam
-Staggered/sealed layers, now fully plastered
From what I could see, the installation was done carefully and neatly. However, I am devastated because I can still hear the neighbours’ voices. The room is currently empty, so the voices sound even louder due to the echo. Once it is furnished, I expect them to become muffled again, but that was already how they sounded before I spent €2,000 on the ceiling.
I was not necessarily expecting complete silence from impact noise, but I genuinely expected a significant reduction in airborne voices. At the moment, I cannot perceive any improvement.
Could the remaining voice noise be flanking through the walls rather than coming directly through the concrete ceiling? Could the wall-supported metal frame be picking up vibrations from the walls despite the isolation tape? Is there anything specific I should inspect or ask the contractor about?
I will add photographs of the installation. I would really appreciate advice from anyone experienced with building acoustics or similar ceiling systems.