Small income - house construction, rental, and co

Good morning dear forum!

I have been quietly reading along from time to time and have long considered whether I should even speak up. But now the time has come because I need external input, whether nice, constructive, or even destructive.

I live in northern Lower Saxony, near the Emsland. Salary levels and construction prices seem to be well below the forum average.

About my situation:
35 years old, single, no children.
Income: €1800 net
Expenses: €800 /month
Equity: €15k in stocks/crypto
1800m2 plot with old house (fully paid off)

Plot prices here are around €60-80/m2, average rent per m2 for new builds is around €6-7.5.

My plan: Renovating the old house would cost as much as a new build. The roof, all windows and doors, heating, and facade would have to be done compulsorily. Hardly worthwhile.
Of course, I also want to build a small house according to my ideas.
However, over the past years I have noticed that as a working person, the plot is too large/too much work for me.
So I could sell part of it, but then I would accordingly have no control over the new neighbor/the construction project. Since I enjoy the freedom and quiet of the 1800m2 (in a settlement), this is a dealbreaker for me.
Alternatively, I have considered building a single-story two-family house on part of the plot and renting it out.
If financially feasible, this could of course especially become an additional security in old age.

The house would cost €130k per 85m2 unit (paint/electrical work completely DIY). Added to this would be utility connections, approval and planning fees.
So roughly I would be at €300k for the complete project.
Because of my age and according to the rent index, only financing over 30 years (including fixed interest period) would be possible.
If I spin the whole thing further, at 30 years and a 1.5% effective interest rate I come to a rate of €1033.
One should probably also consider the new KfW subsidy of €18k per unit, with which theoretically I would only have a monthly rate of €900. (Would I even get 1.5%?)
According to the rent index (€7) I would only get €1200 in cold rent. That obviously leaves little room for maneuver at first. What are the general guidelines for rental buildings?
Through the interest deduction as operating costs as well as the construction costs through the 2% depreciation, some financial relief will of course come afterwards, but should these be factored in?
Additionally, the loan amount is of course steadily devalued by inflation, while rent prices will rise over the years.

Assuming this variant is feasible. How would it look from the bank’s side for another new build for owner occupancy 1-2 years later, especially since theoretically the plot (as equity) would already be allocated to the rental property?

Regards

Where do you currently live yourself? In the old house? What I don't understand: what is the difference between other owners or tenants as neighbors? Both can go well or badly. You can't easily get rid of tenants either. Is there demand for apartments in the area? I think your salary is too low for something like that, especially if you are already calculating with the 2% depreciation. From the rental income, you have to or should also set aside a maintenance reserve, for example. What about a buffer for vacancy?

Hello, yes I live in the old house. It is not uninhabitable, but it is not worth investing a lot of money in it.
However, I do see the difference. On the one hand, 800m2 would bring me 64k€ from a sale (max), on the other hand, after 30 years I would have a debt-free rental property.
In addition, I can simply decide what kind of property is built, where it is located, how the access road looks. I do not have any of that with a sale.
I just have little desire for one or two full stories which might then potentially be right next to my garden, maybe even with a party hut close to my bedroom. With a rental, I simply have more control.
The demand for rental apartments here actually exists. I am not aware of any new building in the whole area that is not already rented out. Development areas are rare. Those currently emerging are so much in demand that practically all spots are taken before development is even complete.
A maintenance reserve would still be possible (provided you don’t calculate with the Peters formula, which I consider somewhat overestimated).
In general, due to my profession, I have the advantage of not being dependent on specialist companies for many things.
Vacancy buffers would of course also have to be created, depending on the financing offer from the surplus or the tax relief.
Of course, the whole story is initially just roughly put together and calculated very tightly, but I do actually see good return opportunities precisely through interest write-offs and depreciation. For me, it would be less about monthly extra income and more about additional security in old age.

Is building even allowed there?

Overall, I consider the income from such an action to be too low. Are there possibilities for improvement?

Is building even allowed there? Overall, I consider the income for such an activity to be too low. Are there possibilities for increases?

Building is allowed. Increasing income is difficult. Just got a raise (in the trades). There is unfortunately rather little industry here.

You don't build for 300k to rent out if you yourself live in the rundown place. Besides, it won't be feasible with the income. Rental income involves risks.