ᐅ Question about Soundproofing with Drywall

We will be building a one-and-a-half-story house with a knee wall height of 1.30 meters (4 feet 3 inches) using solid construction.

The building site is subject to some noise from the nearby railway, which we do not find overly disturbing, especially since the open space in between is partly going to be developed.

We have been advised externally to consider using double drywall boarding on the sloped ceilings of the upper floor for sound insulation purposes. The attic already has a thicker roof structure with 200mm (8 inches) of mineral wool insulation due to the KfW 70 standard.

Now we face the choice between single or double 12.5mm (1/2 inch) drywall boarding in the upper floor. Since we already have a relatively high knee wall and additional insulation in the roof, we are wondering whether the extra investment in double boarding is really worthwhile.

Does double boarding significantly improve soundproofing? Is the additional cost of around 1000 euros (about 1100 USD) a good investment?

Hello,

I can’t tell you exactly how much sound a double layer of drywall will absorb.

But what about your ventilation habits? Do you need a lot of fresh air (open windows) at night?

Have you planned for a mechanical ventilation system with heat recovery?

The best double drywall installation won’t help if the windows are left open…

Regards,

Dirk

We are installing a central ventilation system for both supply and exhaust air.
The windows will generally remain closed.
Windows with SSK 3 glazing will also be installed.

Double-layer drywalling should actually be standard practice anyway, not just for soundproofing purposes.

No idea... I have no experience in this area. Hopefully, some "specialists" will chime in here.

Hello,

Vega82 schrieb:

Since we have already installed a very high knee wall and additional insulation in the roof, we are wondering if the extra investment in double drywall really makes sense.
Does double drywall absorb that much more sound? Is an additional cost of 1000 euros well spent?

I wouldn’t exactly call it “more” insulation; we already use 240 mm (9.5 inches) as our standard thickness.

Double drywall makes sense in your case; for example, in our Cologne area, some residential zones have had it included in the development plan by the city due to high air traffic. The sound insulation rating improves significantly, from 38 Rw,Ct dB with a wall thickness of 125 mm (5 inches) to 55 Rw,Ct dB or even 57 Rw,Ct dB, depending on the insulation thickness. If there is frequent train traffic nearby, I would recommend following your site manager’s advice.

@One00

Double drywall is not a usual standard because it is not necessary everywhere.

Best regards, Bauexperte