Unpredictability of construction costs - Will the project fail because of it?

The building application has already been approved; due to the flexible development plan, it went through the exemption procedure.

Then there should be a plan of the property with exterior facilities and elevations available.

If you want to build the terrace on the west side, then it must be elevated or the ground must be filled. Those are also costs.

An experienced planner could surely have designed that according to your wishes. Without a basement and retaining walls.

AB? There is an extra bathroom with a shower planned.

AB: storage room.
Washing machine connection is missing… fitting kitchen, sleeping, and living room into 17 sqm and then selling it to the authorities as a granny flat is bold.

But what does it matter to us how that happened. Now it’s about how to make an affordable house out of it!
So focus on that!

Then there should be a plan of the property with exterior facilities and elevations. If you want to lay out the terrace on the west side, then it needs to be raised or the terrain filled. These also involve costs. A skilled planner would certainly have been able to plan this according to your wishes. Without a basement and retaining walls.

We actually found the plan good as it is in the end! Besides, it is what it is now. Should we look for a new architect or construction company and wait another two years?

Let's get back to the question.

I would not build the house like that and due to the unpredictability of the construction costs would reconsider the plan thoroughly.

You do not have any usable offers yet, except for the shell construction, which for inexplicable reasons has already become more expensive today.

AB: storage room.
Washing machine connection is missing... fitting kitchen, sleeping area, and living room into 17 sqm and then selling it as a separate apartment to the authorities is audacious.

But whatever: what does it matter to us how that happened. Now it's about how to turn it into an affordable house!
So focus on that!

All I can say is that an independent energy consultant looked at it and gave their approval. Maybe our washing and drying room also counts, because the entire basement area is separately partitioned?

I can only say that an independent energy consultant has looked at it and given their approval.

But he also overlooked the room height. By the way, I'm keeping my fingers crossed for you! Focus on what said!