Building a home - The beginning is always difficult - How does it start?

Savings banks, banks, town hall, real estate agents, etc. There are many ways to find out if something is coming.

From my point of view, you can also stop here for now.
If you don’t know whether the price per square meter is 30 euros (village in the middle of nowhere), 250 to 300 euros (commuter belt) or 500 euros (real city), everything else is pointless. Why don’t you just use immoscout24 and the like?

With zero euros in equity, it won’t work either.
And the question: Why haven’t you saved until now?

Grandpa is in his late 50s. If he dies at 70 or even 75, you’ll still be in the middle of the loan.
The bank will see it that way too.

Honestly, the more I write:
My feeling tells me that building is not for you.

Unfortunately, I didn’t quite understand the question about the "son-in-law" – sorry!

Well, by that I mean the builder with whom you want to "engage" your dream house.

And how I get from a room program to a lot size is unfortunately still not so clear to me.

That of course requires a "qualified" room program – with square meters behind the room names. Suppose the ground floor adds up to 100 sqm of living space, then that will mean approximately 125 sqm of "footprint" with walls, to put it simply, the slab area. Divided by e.g. 0.4 (the "site coverage ratio" Site coverage ratio indicates the buildable portion of the lot size), that would require 312.5 ("313") sqm of lot. Simply put, that is. The floor area ratio (floor area ratio) is a similar ratio; here it is about comparing the living areas (all floors), again with the lot size, while usually the basement is disregarded – again: it is of course more complicated in detail.

How do I find out, for example, where plots will be developed in the future and at what prices?

Simply put: on the market. Where building-ready lots exist, someone will offer them. Municipalities sometimes do this too, often preferably to locals.

I recently came across the floor plan of the Ytong kit house "innovationshaus 240".

That looks quite nice, as inspiration. However, implementing it like the "original" requires a building envelope of over 16 x 16 m, which is "not found on every corner."

Thank you very much for the many suggestions, explanations, and impulses. Tina, as the title already says, we are still at the very beginning. Therefore, your questions are all ones that we will first ask ourselves. Thank you and for now, good night!

I find it a bit too hectic here. Clarify the plot ratio? From what? Wrong order in my opinion.

What you have to do first is roughly check the affordability. No money, no deal and every wish would be pointless.
You say a 1100€ installment would be possible. For that, you get about 300,000€ credit. Unfortunately, you have no equity.

Now the cost side.
Where should the domicile be located? Answer this, then you can research what a plot of land roughly costs. The state provides BORIS, otherwise just look on Immoscout to see if/what is currently available and what it costs.
You then deduct the land costs including acquisition costs from the budget.
From the budget, you deduct 30,000€ for ancillary construction costs, 15,000€ for the very necessary outdoor facilities, and possibly money for furniture e.g. 10,000€ for the kitchen.
What remains, you divide by 1800€ and get the size of the house with standard equipment.

Roughly speaking.

Does the result go in the desired direction or is it completely off?

- No equity
- 3 children who are just starting to cost money
- A large cabin that is needed
- Limited income

I say "won't work," or "good luck"

best regards

Without equity, I do not see a healthy financing. With the sums being called for today for a new build + all the costs that arise (land, house price, purchase incidental costs, construction incidental costs, outdoor facilities, equipment, etc.) I already see a bleak picture even without a granny flat. At your age, you already need about €80-100k in equity. 80% lending excluding purchase incidental costs should always be the goal. I assume that you would receive [Baukindergeld], but this is not equity, rather a small support in the sense of a voter gift.