Holiday home possible on single-family house property?

Hello forum,

I have the following offer as a plot of land: Single-family house with a floor area of approximately 130m² (gable roof / hipped roof bungalow). The building inquiry was positive. As an idea, I would like to put a holiday home/log cabin on it, which I would primarily like to live in on weekends, for example something like this:

[*]External dimensions: 834 x 890 cm (covered area)
[*]Base dimensions: 780 x 730 cm
[*]Side wall height: approx. 252 cm
[*]Ridge height: 381 cm
[*]Usable area: approx. 46.6 + 19.5 m²
[*]Room volume: 148.5 m³
[*]Roof area: 74.4 m²
[*]Roof pitch: 18.6°
[*]Wall thickness: 70 mm

My questions about this
-Is this possible with the requirements?
-Are such houses durable?
-Are they also permanently habitable in terms of legality and quality of life?

I have the following offer as land: Single-family house footprint approx. 130m² (gable roof / hip roof bungalow). Building preliminary request was positive. As an idea, I would like to place a holiday home/log cabin on it, which I would primarily like to live in on weekends, e.g. something like this: [Bild] Base dimension: 780 x 730 cm Roof pitch: 18.6° Wall thickness: 70 mm

I consider a 130 sqm plot practically unbuildable. You have to comply with the permissible roof pitch etc. even with a very small house (except for a tool shed for rakes and lawn mowers), and the house with 57 sqm would require a floor area ratio I of just over 0.4. Regarding the wall, I hardly see the valid energy-saving ordinance as enforceable, which however, as far as I know, only applies to year-round residential buildings.

Building preliminary request was positive.

Then the permissibility should also be clarified in this case (?) I do not see a permanent residence possible in such a house. A permanent residence as a main residence could in principle be possible on the plot, but that would then probably entail that the house would have to comply with the energy-saving ordinance. How did you name the building in the preliminary request?