Material exterior walls and interior walls (KfW 55 standard)

With a small construction contractor from the region. Bungalow, heat pump, chimney for the fireplace, electric shutters, no controlled residential ventilation, no photovoltaic system, no KNX. We will install the fireplace ourselves.

We are doing the same with a small construction company (approx. 20 houses per year). Your price is good :)

We have built 17.5cm sand-lime brick + 14 cm ETICS (with you then more due to KfW55). Interior walls in 11.5cm sand-lime brick.

I am very satisfied with the exterior walls, no problem acoustically. For the interior walls, however, I would also use 17.5cm thickness if building again (especially for the bedrooms). The bricks inside have a different bulk density than the bricks in the exterior wall and do not insulate quite as well at the same thickness.

The bricks are specified with a strength class of 2.0 on the outside and 1.6 on the inside.

We built 17.5 cm calcium silicate brick + 14 cm ETICS (with you then more because of KfW55). Interior walls in 11.5 cm calcium silicate brick.

I am very satisfied with the exterior walls, acoustically everything is no problem. However, if I were to build again, I would also make the interior walls 17.5 cm thick (especially for the bedrooms). The stones inside have a different bulk density than the stones in the exterior wall and do not insulate quite as well at the same thickness.

The stones specify a strength class of 2.0 on the outside and 1.6 on the inside.

All right :-) We are building with 36.5 cm Poroton without ETICS. Inside 17.5 cm, except for the drywall walls, which we will determine so that a later (after years) change can be carried out more easily.

36.5 can also work with KFW55 in my opinion, if the envelope is calculated overall and not built according to the reference value. At the end of the day, it’s all a question of price or where effort is put in at which point. Basically, a better wall never hurts ;)

Technically, the most sensible from an energy perspective is actually ETICS; interior mass, exterior insulation. Depending on the design, there are also other systems than the classically associated "we glue Styrofoam outside" up to existing facades, etc., which are not usually found in the typical single-family house spectrum or even the standard construction service description.

As already noted, there are significant differences in sound insulation with windows, which are often significantly worse than the stones themselves.

The stones on the inside have a different raw density than the stones in the outer wall and do not insulate quite as well at the same thickness.

The insulating ability of sand-lime bricks is completely irrelevant anyway, as it is almost nonexistent either way. I think lighter stones were chosen inside (slightly) due to structural considerations. Our sand-lime brick walls are 15 cm thick both inside and outside and all have a raw density of 2.0.

The stones are specified as having a strength class of 2.0 on the outside and 1.6 on the inside.

Be careful, raw density is something different from stone strength. The latter for sand-lime bricks is regularly around 12 (or 20), so in a completely different range than the raw density.

we wanted a stone with plaster inside and outside, and built/glued, no renovation measure ETICS already in the new building