Little sound insulation in the solid house - what could be the reason?

Hello everyone,

we have been living in a solid house for almost 6 months and are very dissatisfied with the noise insulation. The masonry of the exterior walls consists of 36.5cm and the interior walls of 24cm Wienerberger Poroton bricks. The windows are triple-glazed, the interior doors made of hollow core boards. Normally, one would expect to hear little from the outside world inside the house, but sometimes it feels as if all the windows are open because you can hear the voices of people walking past the house inside. The closing of car doors as well as passing cars (30 km/h zone) is also very annoying. The noise situation inside the house itself is by no means better. Our bedroom is located right next to the children's room. At normal volume, it is not possible to have a conversation in the bedroom, and if the TV is on, it also has to be set very low, otherwise our child wakes up. When the washing machine or dryer is running in the basement, you can also hear it all the way up to the bedroom, although the rooms are separated by one floor and 2 doors. Do you have any idea why we have so little sound insulation? Previously, we lived in a rental apartment and had significantly better sound insulation than now. Thank you very much in advance for your help.

In the house, the cause can only be due to bridging in the formwork, meaning incorrect execution of the connections. Possibly also poorly closing "cardboard doors"? If it is loud from the outside, the windows are often incorrectly adjusted. In the attic, it can be due to the roof structure.

Do you have any idea why we have so little soundproofing? Previously, we lived in a rental apartment and had significantly better soundproofing than now.

Do you have a ventilation system? If yes, which one?

The cause in the house can only be due to bridging in the partitions, i.e. incorrect execution of the connections. Possibly also poorly closing "cardboard doors"? If it is loud from outside, the windows are often incorrectly adjusted. In the attic, it can be due to the roof structure.

The doors are already better, but with solid chipboard panels the sound would be reduced even more. We should really take another look at the attic. We also suspect that the sound is transmitted between the children's and bedroom through the attic. Although the attic is insulated with mineral wool, a lot can still be optimized with wood chipboard panels. For the windows, we have window rebate ventilators for circulation. These probably let in a lot of noise along with fresh air...

Do you have a ventilation system? If yes, which one?

We do not have a ventilation system, but regulate air exchange with window rebate ventilators, which are probably also the reason for the noise.

So our plan now will be to expand the attic with wood chipboard panels and to replace some doors with ones made of solid chipboard panels.

Thank you very much for your help.

It is quite possible that the attic floor is installed over the partition walls without insulation strips. On the floor, an insulation strip is placed between the floor and the wall to decouple the sound. You should also do this with the ceiling, but it is no guarantee that it will improve. A lot of mass also helps; unfortunately, adding more mineral wool does not make much difference... If the ceiling is reinforced with substantial mass, the load-bearing capacity must be considered. It is strange that the washing machine can be heard clearly upstairs. With some luck, you might be able to find out how the sound is transmitted. Turn on the washing machine and "note" the volume in the hallway/room in front with the door closed; if it is lower than upstairs, the sound is probably transmitted through the masonry.

Unfortunately, this is almost normal nowadays due to the construction.