ᐅ Sound insulation for an old wooden beam ceiling

Hello everyone,

I want to renovate an old wooden beam ceiling. The floorboards have already been removed, the joists will be doubled where necessary, and then OSB boards and dry screed will be installed as the new floor. Tiles will be laid on top of this.

I’m wondering how I can ensure sound insulation for the ground floor. Is mineral wool between the joists sufficient here (in addition to insulation strips on the beams and at the wall), or would a loose-fill insulation be recommended? I am limited in how much weight I can add. Is there an alternative with low weight but good insulating properties?

Thanks and best regards

Sir_Batman schrieb:

Hello everyone,

I want to renovate an old wooden beam ceiling. The floorboards are already removed, the joists will be doubled up where necessary, and then OSB boards and drywall underlayment will be installed as the new subfloor. Tiles are planned to be laid on top.

I am wondering how I can provide soundproofing to the ground floor.

I understand the construction as follows:
- Impact noise is the main issue plus
- Creaking of the beams
when the floor is loaded.

To reduce creaking:
possibly insert some longer screws where there is movement.

To reduce impact noise:
possibly use two layers of OSB (each thinner) with an impact sound insulation membrane between them.
Mineral wool helps thermal insulation but provides little sound insulation.

However, the construction details would need to be known more precisely.

Current situation:
from the ceiling of the ground floor
1. Plaster on straw mat (?)
2. Formwork boards about 20mm (0.8 inches)
3. Beams spaced approximately 60-80cm (24-31 inches) apart
The beams may be doubled up to even out any unevenness.

4. OSB boards on the beams
5. Dry screed on top of the OSB
6. Tiles on top of the dry screed

The question is whether an infill material should be placed between the beams.

The OSB and dry screed are installed using adhesive felt to prevent squeaking. However, if there is a bathroom above, ideally noise should be minimized in the room below.

Then you need a loose-fill material with high mass. Perlite can also be used as loose-fill; it is somewhat lighter. Double-layer drywall provides almost no benefit for floors, and mineral wool does not reduce impact sound for this type of ceiling.

Myrna_Loy schrieb:

Then you need a loose fill with a lot of mass. Perlite as loose fill is also an option, which is somewhat lighter. Double boarding on floors hardly improves anything, and stone wool does not reduce impact sound on such ceilings at all.

I looked it up again; there are high-density stone wool boards from Rock*****. I would install those between the OSB and the cement board (dry screed). This also follows the manufacturer's installation recommendation. OSB serves as a load-bearing substrate.

The problem might be the boarding underneath the joists. It may not be strong enough to support 40-50 kg/m² (8-10 lb/ft²) of loose fill.
Does the loose fill need to completely fill the space between the joists and the OSB?

There are very informative brochures available for download online from leading manufacturers, presenting various options. Soundproofing wooden beam ceilings is definitely not simple and usually requires a combination of several measures.