Is a building permit necessary for an extension?

Does anyone perhaps know a cost-effective solution for the planning.

Sure, ask the company that is going to carry out the extension. They often have a technician or draftsman on hand who can plan something like that.

Has anyone ever found a company that actually does this? Either the companies don’t do it and refer to architects, or they are well-known companies with pharmacy prices (who execute it perfectly). But they just pass on the costs for an external architect with an additional charge.

Hi, that's the problem, I don't want to go along with this price gouging. 6000 euros for the planning of one room.

Has anyone ever found a company that actually does this?

Well, I like to think so. We approached a civil engineer to see if he would handle the building application for a small extension. For items 1-4, he gave us a very reasonable offer – I think something around 2K, with which we could have started building. That would have to be enough for the OP. But we preferred that he also do item 5. That came to 12K.

On what basis were the 6000 euros calculated? It is not as if only one room is being planned, but an extension and connection to an existing house. And then also a bathroom and not an office. For this, the basics such as statics, substrate, etc. must be determined, and the connections for various materials and lines must be planned and permits obtained. To judge whether it is usury, a counteroffer, or reasonable for what is to be built, more information would be needed. Almost two years ago, we had an offer from an architect for [Leistungsphase 1-4] for a two-story extension with 24 sqm per floor of just under 4000 euros.

It is only one floor and two walls are already standing. But a defensive offer can already be made.