Cultivation - Building window - Building permit

Hello everyone,
I have been a silent observer of the forum for a long time and am now about to buy a house. Financing is secured, and the second and third viewing appointments are already scheduled. My better half and I are convinced, unless there is still a small issue that causes us concern.
There is an extension about 15 meters long, consisting of 2 rooms in a row. The front one is tiled and also has a small bathroom as an adjoining room, the room behind has more the character of a shed but, if converted, would provide an additional living area of about 35 m². According to the development plan, the entire extension or its type of use is residential area.
I have already spoken to the building authority; one is allowed to renovate and repair the room, but if one changes something about the structural integrity (new roof beams, large glass windows), a building permit is required.
Now to the question: The extension is about 9 meters behind a newly designated building boundary. How likely do you think it is that a roof renovation will be approved by the building authority since the project is outside the building window?
Many thanks in advance

I have already called the building authority; one is allowed to renovate and repair the room, but if one changes something in the structural statics (new roof beams, large area windows), a building permit is required. Now to the question: The extension is located about 9 meters behind a newly established building boundary. How likely do you think it is that a renovation of the roof will be approved by the building authority, since the project lies outside the building window?

If the existing roof is "only" replaced with newer materials, perhaps a window replaced in the existing size, and otherwise the structure is not altered, I see no reason why the building authority should refuse the permit. However, if you want to change the roof pitch – for example, from flat to gable roof and thus generate more living space "through the back door," the authority will very likely reject the application. Rhineland regards

The part is to remain as it is. The existing gable roof is to be repaired, possibly with new roof beams added (if the craftsman thinks so - possibly a structural engineer is also needed?!), insulation underneath, and drywall. The issue with the windows is a bit tricky. There is only one window. Possibly new large-area windows facing the garden. Because one window is very little by today's standards. From the outside, everything except the windows should remain the same.....

Hello Tommy,

I recommend in such cases to obtain the building file or at least gain access to it and make copies. This can be done with the current owner's consent even before purchase. In the building file you then see (hopefully)

1. The building application or at least a building notification of the extension => comparison with the development plan!
2. The condition of the building line or the area at the time of the building application for the shed/extension
3. The historical development of the building - can be important regarding old legal situations/protection of existing structures
4. Then go to the architect and submit very specific renovation applications

I would not put any weight on telephone information, but generally I see it as a construction expert that one is allowed to renovate/renew as long as the exterior shell is not significantly changed. However, I have (to put it cautiously) experienced more than once that there are slight differences between (old) building applications and the current state and you have to ensure that what is standing today also enjoys protection of existing rights or was once approved - and completely so. For very old huts, it is also worth a visit to the city archive; there I found even more about my house than what was stated in the exposé.

Best regards
Dirk Grafe