New construction KFW 55 - wall construction

Good day,

we are currently planning our single-family house and have two offers for a KFW 55 house.

The two providers differ, among other things, in their wall construction, which is not insignificant in our considerations – especially regarding sound insulation.

I know that wall constructions with their advantages and disadvantages have already been discussed several times in terms of sound insulation, fire protection, thermal insulation, climate, installing kitchen cabinets, etc. I have also studied the matter extensively but would still like to get your opinions.

Exterior walls:
Provider 1: clinker brick, air gap, ETICS, sand-lime brick + gypsum plaster (wall thickness approx. 50 cm, further details are not yet available)
Provider 2: 11.5 cm clinker brick, 2 cm air gap, 1x 6 cm and 1x 8 cm core insulation mats staggered (mineral fiber mats – hydrophobic/water repellent) WLZ 035, 17.5 cm aerated concrete, compressive strength PP2, WLZ 010 + lime mortar plaster => wall thickness approx. 46 cm, U-value 0.16 W/m2K.

Interior walls for both made of sand-lime brick

The different wall thicknesses do not matter to us.
Since both must be suitable for KfW 55 anyway, we assume that sufficient insulation is given in both cases (especially with winters that are increasingly mild).

A major argument for us, on the other hand, is sound insulation, as we prefer it to be a bit quieter and do not necessarily want to hear everything from outside when the windows are closed (highway approx. 500 m away, with only fields in between).

Due to the sand-lime brick, Provider 1 should offer absolutely sufficient sound insulation. But how does Provider 2 compare? Since the aerated concrete does not contribute much, how does it look with the core insulation mats + air gap + clinker brick? Can a rough comparative estimate be made here?

An additional advantage of Provider 1 is that both exterior and interior walls are made of one material, thus definitely ensuring the same shrinkage behavior.

Both offers are roughly equal in price (with initially negligible minor differences in other trades).

Perhaps also a brief question about the interior plaster. Lime mortar (I hope without cement) with Provider 2 might be somewhat better, as it leaves no chance for mold. Due to controlled residential ventilation, gypsum plaster should also be equivalent and completely sufficient. Am I correct here?

Looking forward to your opinions.

Riepirat

Tip: absolutely pay attention to the windows! What use is the thickest wall if the 4*2 m window element comes along with 36 dB. Many would probably prefer lime over gypsum... alkaline, vapor-permeable.

Correct. The question about the sound insulation rating is already included in my list of questions. Thank you very much.

I technically can't help you - I only have a suggestion for you: Have reference houses shown to you and test the volume. Take a phone and measure the decibel level on your property (500 meters to the highway is a) extremely high background noise + b) high amplitudes from loud trucks / motorcycles / exhausts). Go with a song / car noises to the reference houses and have someone play the song / car noises in the right volume in front of the wall - this way you'll get a relatively good impression.

Thank you very much. But we have already decided on KS. I think we are not making a mistake with that.