Thin exterior wall in old building, 12 cm exterior wall

Hello dear forum readers,

we are renovating a house from the 70s. According to the plan, the bedroom (which borders the neighbor’s garden) has a 12 cm exterior wall. No wonder you hear every sound as if you were "right in the middle of it" we ordered good windows, but if all sounds pass through the wall, that doesn’t help much how can we best ensure sound insulation, from the inside or from the outside "build in front" and with what? Many thanks in advance for the help!

PS: in front of the bedroom there is a "small storage room" that we have insulated with rock wool and Isofix foil, because previously you could look through the bricks into the garden at individual small spots, it was that open.... the room is about 1.50 meters wide, then comes the 12 cm bedroom wall.

Best regards

Hello,

we are renovating a house from the 70s. According to the plan, the bedroom (which adjoins the neighbor's garden) has a 12 cm exterior wall. No wonder you hear every sound as if you were "right in the middle of it" we ordered good windows, but if all sounds pass through the wall, that's not much use how can we best achieve soundproofing, from the inside or by "building out" from the outside and with what?

This is airborne sound and there is really only one reasonable way to reduce it. Cut grooves in the screed in front of the wall and build a second wall - preferably made of aerated concrete blocks - directly on the raw ceiling (attention to structural engineering). It’s not exactly cheap and it probably won't completely block out the noise.

Find an architect/structural engineer you trust and discuss possible solutions with him; everything else is groping in the dark

Kind regards

The question is indeed directed at sound insulation. With a 12 cm exterior wall, thermal insulation should also be a topic. This is especially the case when something in the building envelope system of the house is changed - as intended with the new windows. It is not uncommon for building physics problems to occur after a partial energy-related modernization - specifically, mold formation can result especially in the transition between well and poorly insulated components.

Caution is also advised as to whether, for example, a building permit is required for an additional outer shell. For maintenance/modernizations, this may not be necessary. However, in many federal states, any alteration of a building requires approval - depending on the scope of the change, it must be examined whether a building application is necessary - no matter how exaggerated that sounds.

I recommend having a concept created before installing the windows on how insulation (sound and/or thermal insulation) and the installation of new windows can be sensibly combined. If it comes down to an outer shell, the windows would be placed structurally favorable further to the exterior wall side.

Overall, structural stability should not be overlooked in the process. For a masonry wall, 17.5 cm is considered the minimum thickness for load-bearing walls - for an exterior wall, I assume it is load-bearing. Consulting a professional is my urgent recommendation.

By the way, calcium silicate bricks are certainly good in terms of (air) sound insulation, but they are also correspondingly heavy and not very effective regarding thermal insulation.