Change of use in the outdoor area

Hello. We want to convert a horse stable into a residential house; this is to be done in the outside area as part of a privileged development when abandoning agriculture. The stable is quite tight in terms of external dimensions (11.0m-6.5m), which will be cramped for a family of five. Attached to the stable is a laundry room of about 15 sqm as well as a small farmhouse, which should actually be demolished because it is extremely dilapidated. Does anyone have experience with how residential space, which is to be demolished elsewhere, can be cleverly and legally securely integrated into the horse stable via dormers/gables or extension/shared use of the laundry room? Unfortunately, the building authority gives us different information; one said we could at least redesign the laundry room as living space, the other says exactly the opposite. We are now unsure about our further approach (directly paying for planning with an architect at the risk that everything will be rejected) since the building would only be an option if enough living space is created. Thank you

How did you get the information? Only verbally or within the framework of a [Bauvoranfrage] (for which you do not need an architect)?

With the [Bauvoranfrage] you are on the safe side.

How did you get the information? Only verbally or within the framework of a building preliminary inquiry (for which you don't need an architect)?

With the building preliminary inquiry you are on the safe side.

It was only a verbal statement from the various offices.

Oh, I thought a building preliminary inquiry was always only possible in connection with an architect?

This is what your municipality requires from you (quote from the homepage of the city of Wermelskirchen), if you can prepare the documents yourself or already have them, you can submit the building preliminary request yourself:

4. Building Preliminary Request/Preliminary Decision
Whether a plot of land can be built on at all with the intended structure is not always easy to answer. A building preliminary request can be submitted before purchasing a building plot in order to establish the necessary legal certainty.

The decision made in the preliminary decision by the building permit authority is binding for the corresponding building permit procedure and saves time, as fundamental criteria have already been checked in this preliminary request. However, the binding effect of a preliminary decision expires if the building application deviates significantly from the building preliminary request. The preliminary decision does not replace a building application and does not authorize the start of construction. Only through the building application are the conditions for the construction project clarified in detail; in particular, it regulates building code matters such as neighbors’ rights, boundary and building distances, building height, technical execution, etc.

The written application for the issuance of a preliminary decision must be accompanied by at least the following documents:

[*]1 site plan at a scale of 1:250 or 1:500
[*]1 overview plan at a scale of 1:2500 or 1:5000 (in the case of a location outside the town)
[*]1 building description with dimensions for the building structure
[*]1 building design sketch at a scale of 1:200 or 1:100 (if a more comprehensive decision through the preliminary request is desired).

These documents must be submitted in triplicate to the Building Administration Office. The administrative fees for a formal preliminary decision range from €50.00 up to 1/1 of the approval fee, depending on size and administrative effort. These costs are partially credited against the later building permit fee! The preliminary decision is valid for two years but can be extended.