Shell construction offer - what do you think?

We have received the following offer for our shell construction? What do you think about it?

About the house: 1.5-story single-family house, 153 sqm living area, dimensions 9x11, garage 6x9 including open storage area. KfW value between KfW 55 and 70, approximately 60. Two bays on the sides. Attention: shell construction garage is included.
Roof for garage and house, as well as roof truss, are self-performed. Also the ceiling on the upper floor (made of wood) and the small bays from window height on the upper floor are self-performed, as it is a timber frame construction. Staircase and garage door are also not yet included.

Not bad for the scope of services, I think. Including clinker brick, garage, interior plaster, screed, roller shutter box. But why aerated concrete? You won't rely on it for insulation (160mm WLG 035 in double-shell masonry). Poor for soundproofing on the inside. What about calcium silicate brick? There is a bit of on-site work to be done in the earthworks, especially disposal. I still see a cost risk in the quantities of concrete and steel, which are apparently only estimated. There could still be something in there.

Thank you for the first responses. The interior walls are made of sand-lime brick. Only the exterior walls are not. To be honest, I don’t know why he chose it that way. I can talk to him about it again.

Oh yes, that's true. But there is still aerated concrete in the attic, I guess I got stuck on that.

That is all extremely cheap, interior plastering 6000 euros what is that supposed to be? Normally you are easily at double that, possibly even at triple.

Interior plaster 6000 euros what is that supposed to be? Normally you are easily at double that, possibly even triple.

It is 7600€ gross. It was about 500€ more for us, house of similar size with a mix of gypsum and lime-cement plaster. It was done very well for us.