Execution plans changed without consultation!!

I would demand the dismantling. Something like that is not acceptable.

Completely unrealistic If anything, the window opening can be changed and the partition wall renewed, provided it is not load-bearing.

Thanks ☺ but I think €1,000 is not quite enough!

Not enough for what? Quantify the damage. And please report what the planning office offers in terms of compensation proposals …

Completely illusory If at all, you can change the window opening and renew the partition wall, provided it is not load-bearing.

That’s what I meant by dismantling. And if it is a load-bearing wall, then they have to come up with something. As an architect, I cannot change room layouts and facade divisions without a written "go" from the client. Definitely no.

Completely illusory
If anything, you can change the window opening and renew the partition wall, provided it is not load-bearing.

You can’t reach it for what? Quantify the damage.
And feel free to report what the planning office offers as compensation proposals …

I will keep you updated on what the response will be! When I said "not enough," I meant the €1,000 for a possible dismantling! It will be a bit more than that… ‍♂️

We are building together with a planning office and we approved, signed, and submitted the building application together with the architect of the office! We then received the building permit! So far, everything is normal!

So the permit came to you. From this, I read that you are the builders, not buyers of a developer’s house. What then is meant by building "together" with the planning office – what stakes do they have in the matter?

Now, during the measurement of the basement floor, we noticed that the children's rooms, which were actually planned to be the same size (according to the building application each 17 sqm), are different sizes (one children's room is 20 sqm, the other 15 sqm)! Our site manager couldn’t explain it either at first! He then sent me the execution plans!

Changes between the design and building application plans should have been communicated to you. Changes after the building application plans would have required corrections.

On these plans, the architect changed (reduced) the distance between two windows in the basement, which caused this size difference! The reason was that otherwise the windows in the basement would not have been aligned with those on the ground floor!

I do not understand why the change in the window position led to a change in room sizes (so I am waiting for your plan drawings). Normally it is the builders who move windows "on the fly." I cannot see what could have prompted an architect to do this. From copyright law alone, I do not consider it covered.

Thank you ☺ but I think 1,000€ isn’t quite enough!

This is how it’s done: you come to an agreement! …because the dismantling for the BU is doable, but in the end you almost only have disadvantages regarding time. The BU will neither cover your standby interest nor any other collateral damages. A complete dismantling is disproportionate. You come to an agreement and try to get a little something out of the GU. If you want to litigate despite the offer: even a judge would not see the imbalance between the two rooms and would plead for common sense. If the wall has to be removed, I would mediate this despite the windows. For example, you could have a built-in wardrobe measured for the other room in both or the larger room. The GU pays the carpenter! Don’t get me wrong: I also think that independent planning is outrageous. Show the floor plan: maybe we can see an idea for the wall and the two rooms that you (still) don’t see.

Don't get me wrong: I also think that the independent planning is outrageous.

I would rather speak of "unauthorized[I]" and probably also of "unlawful".