Is the base plate properly sized?

Yes, we do. The first planned appointment is the shell construction inspection. That was the suggestion of the building savings contract. ‍♂

Hmm. So he/she comes when the foundation slab is in place, the internal masonry is standing, the ceiling is poured, the ring beam is finished.
So if it's already too late, a mistake really would have happened here :rolleyes:

No idea if I understood your problem correctly.. I only remember that back then with our floor slab, I thought it was too small.. Several centimeters were missing all around. After measuring, I had a sleepless night. But it turned out that the first row of stones was laid extending about 5 cm all around. That made the room dimensions fit again and everything was fine. You can see that in the picture.. I hope...

That would not work here, because you cannot simply support the outer wall in the air or on gravel or sand.