ᐅ Soundproofing timber beam ceiling (accessible only from below) plus insulation

Hello,

who can give me advice on improving sound insulation in a condominium?

Initial situation:

• Old building, built around 1930
• Ceiling to the floor above: wooden beams
• On each side of the beams, a battens structure
• On the battens are formwork boards: two directly on the battens, with the next formwork board resting on those, and so on
• Clear height from the bottom edge of the formwork board to the bottom edge of the beam: 9 cm (3.5 inches)
• Battens will later be installed below the beams
• The floor above probably lies directly on the beams without impact sound insulation
• The floor above is NOT accessible, as it belongs to the neighbor
• All noises from the neighbor above can be heard almost unfiltered
• Ceiling height is limited in typical old building style; I do not want to reduce it by more than the battens (3 cm x 5 cm) (1.2 inches x 2 inches)

My proposed solution:

• Insulation with mineral wool between the beams. The battens create a stepped cavity, which is not ideal but cannot be changed
• A vapor barrier under the mineral wool
• Battens installed "loosely," for example with resilient strips
• Plasterboard panels mounted onto the battens
• "Floating" connection to the walls

Following questions:

• What else could I do to improve sound insulation?
• I want to combine thermal and sound insulation as effectively as possible
• I found sound insulation foam panels online that are sometimes used for musicians' practice rooms. They are said to be fire-retardant, but is this a good idea? A full-surface installation would only be possible on the battens’ level
• The resiliently mounted battens are said to contribute to sound insulation...

Who has a similar situation and good experience with soundproofing? Any tips are much appreciated.

Best regards,
Frank

The considerations are correct and, in my opinion, sufficient. You can’t achieve much more from below using simple methods. I just don’t see the point of the vapor barrier. If the floor above is heated, it would be unnecessary.

I’m not a fan of “miracle products.” Heavy-duty membranes, etc., may be justified in exceptional cases, but for a “normal” ceiling, they might be a bit too much.

If you replace the mineral wool with wood fiber insulation boards, you can achieve significantly better soundproofing. The more mass, the better the sound insulation. However, at the same thickness, these boards provide slightly less thermal insulation than mineral wool.