House extension - beginner questions

Hello dear community...

I hope you will forgive me if I ask some silly questions here - but when it comes to house renovation/extension, I am an absolute beginner.
That’s also why I registered here - in the hope of getting some answers and tips for our project.
Thank you in advance for all your answers!

Regarding my/our concern:

We would like to create additional living space by adding a storey to our existing house.
The following idea is wandering around in our heads (if something like that is even feasible):
The little used balcony should be "closed in" and built up higher.
The existing asymmetrical roof should then be made "even" on both sides and equipped with dormers to be able to use the attic.
Attached are also 2 pictures - just to get a rough overview...

This is the rough idea of what is going on in our layman minds.

Now as a concrete question to the community:
Who does one have to contact with such an "idea" to check whether and what is feasible?

I know - the information is quite sparse.
If further information is needed, I would try to gather and provide it to the best of my knowledge!

Thanks again to you all and have a nice evening

I would ask an architect. Preferably someone who frequently deals with remodeling/renovation and not a pure new builder. An architect can definitely help you. A [GU] could also be possible, although that might be a bit too specialized for them. Most [GUs] are specialized in new buildings.

Looks like a single-story construction. That would "forbid" closing off the balcony to the living space. First, read the development plan to see what is possible, then consult an architect for the planning.

The twin character of the semi-detached house may also have to be maintained.

Hello and thank you very much for the answers...

The house has 2 full floors - on the 1st floor there are 4 fully fledged, albeit quite small rooms, one of them with access to the balcony.

Do I get the development plan at the municipality or does the district handle that?

The house has 2 full floors - on the 1st floor there are 4 fully usable, albeit rather small rooms, one of which has access to the balcony.

No, the house shown is a single-story house. Just because a house has two or even three floors does not mean that these are legally full floors. Here it is clearly visible that the ground floor has a larger floor area than the attic. Due to the asymmetrical roof and the use of the "bay window" as a balcony, one can conclude that they tried to make the most out of the single-story design here.

However, this does not exclude that two-story construction is permitted and it was only built as a single story. The development plans are now listed by many municipalities on their websites. Just look under the department of building authority or inquire there by phone.