Completely renovate and modernize the house from 1986 - Costs?

Upper floor currently However, the 120m2 on the upper floor are to be fully utilized. Bedroom, dressing room, bathroom, 3 children's rooms and children's bathroom

Somehow I have the feeling that the renovation is getting more expensive the more information comes in...

I would really consider a demolition.

Tear off the part. With the new information, the house becomes a money pit that will be more expensive than a new build...

Great that one of the children could already practice being the boss with a child from the anteroom, hehe.

But the 120m2 on the upper floor are to be used completely. Bedroom, dressing room, bathroom, 3 children's rooms and children's bathroom

Yes, on the upper floor instead of the current attic already - but the new attic above the then upper floor is not supposed to be used as living space as well?

With the new information, the house is becoming a money pit that will be more expensive than a new build...

I don't have enough information yet to make such judgments.

I would seriously consider a demolition.

At least rather a partial demolition than an additional storey.

Somehow I have the feeling that the renovation is becoming more and more expensive the more information comes in...

Especially qualitatively, I see too little clearly. Ground floor, basement/underground floor, plot/building envelope ... and of course pictures of the condition (outside & inside).

So from 1+D (total 160 sqm) to 2+D with attic space but then not also additionally fully developed for living?

Hmm, I ask you whether the floor area ratio and the development plan are still being complied with?

But the 120 sqm on the upper floor is to be fully utilized. Bedroom, dressing room, bathroom, 3 children's rooms and children's bathroom

Am I the only one seeing black squares?

Hmm, do I ask you whether the floor area ratio and the development plan are still being adhered to?

Me, why? - I don’t know the development plan here.

Am I the only one seeing black little pictures?

One little picture, above and below equally high black border. Just a phone screenshot.