Construction costs mini-bungalow (approx. 50m²)

Just post your 50 and 65 sqm designs here, then they can be concretely improved. And take a look at the single houses "Fun" and "One" from Kern, I just found them. They wouldn't be for me, but they seem to me to be realistically buildable examples.

These core houses are expensive, though. Phew.

Just post your drafts for 50 and 65 sqm here, then we can specifically improve them.

What I currently have as a file on my computer is the 2-room layout of a 64m² house: (8X8m, calculated without area losses due to walls)... In the hallway there are 3 doors: to the living-dining-kitchen area, to the bathroom, and to the bedroom. The utility room is accessible from the bathroom. The kitchen is located basically "top left". In the bathroom "top left" there is a walk-in shower (glass wall on the right), next to it on the right is the toilet, then a window, and then the sink, etc.... Whether 64 or 65m², it doesn’t really make a difference in planning terms.... The 50m² variant: Is slightly larger than 7X7m, so a downsized 64m² version. Except for 2 differences: bathroom + utility room are combined into 1 room (approx. 10.5 m²) and the sleeping area is accessible through the living area via a wide sliding door and not through the hallway. By opening the sliding door, a 35m² area (cooking/living/sleeping) is created, which is meant to provide as good a sense of space as possible despite the very small total living area. It is very important to me to have the most open floor plan possible, although I have to say that this "loft-like" open version is already the most extreme one...

... To convert the mentioned net areas to gross areas, the buildings must be approximately 1m larger. (Compensation for area losses due to the walls) instead of 8X8 ....9X9m - then 65m² living area net and instead of 7X7m 8X8m - then 51m² net

To get from the mentioned net areas to the gross areas, the houses need to be about 1m larger.

Then the 9x9 house would suit and work for me, but it would no longer be "small", and with a finished attic it would also be conceivable for a small family.

In the design, I would move the bedroom to the top left and make the hallway open towards the living area, for example with a half-height wall.

I have measured your rough draft, adjusted it to 8.99 x 8.99 m, and basically adopted the dimensions; the load-bearing wall is located approximately in the middle under the ridge beam. That gives me 63.43 sqm (after plaster deduction) with 80.82 sqm built-up area. You see, with 21.5% such a tiny house burns relatively much ground area for walls. I wouldn’t see a clever staircase position for adding a floor that way, but you could still play around with that.