New construction in the outskirts (former farmstead)

There are 4 outbuildings on the property.

1x former threshing barn
1x 3-car garage
1x former pigsty
1x 4-car garage for caravans etc.

The lady at the building authority told me back then that we were allowed to convert one of the buildings into a residential house. 50% of the basic structure must be retained. The external dimensions must not be changed! (It may be clad with bricks or plastered, a new roof is also allowed, windows as well, but no bay windows or dormers, for example.)

--> an oral statement is not worth much
--> the statement is actually quite clear. This should exhaust the scope of possibilities, whereby 50% basic substance sounds fair.

That was a general statement from the lady after she looked at the property on Google Maps.

There was no argumentation from US behind it that might possibly move her to consider a new building.

I will upload the argumentation from our architect later. It describes everything in detail why we consider a renovation disproportionate.

Our architect also said that we won't "get there" if 50% must be preserved...

That won't work.
Conversion within the existing volume is often approved, demolition and new construction without privileging almost never.
That demolition and new construction is often financially better is old news and will not change the decision.
The pigsty is hardly suitable for a conversion, too narrow, too low.
What does the threshing barn look like?
I still wish you good luck and please keep us updated.

Attached is a picture of the yard.

1. Is the pigsty, which should be avoided if possible...
2. Is the threshing barn, which would be difficult to renovate. The masonry shows severe cracks, and the building houses the heating oil tanks for the main residential building, etc.

I have placed the scale on the picture...

Hey,
so with us you wouldn't get away with that, no matter what the building authority says, because the final decision is made by the district.

Conversion of former stable/outbuildings is only allowed for privileged people, meaning those who practice agriculture.

Fingers crossed for you and I'm curious to see how it continues.