House construction in Baden-Württemberg - Planner first or bank?

There are always two approaches:

1) Fixed living space and see how much money it takes or
2) Fixed amount and see how much house you get for it.

Rough house prices can be given to you here as a guideline if you roughly know how big the house should be. You can always adjust later.

You can also roughly be told how much money the bank will provide if you know how much money is available monthly for the house and how much equity should go into the house.

Then you can see if you can somehow align both numbers.

I can help you with the money:

How much cold rent do you currently pay?
What monthly savings performance do you provide that can/should be discontinued when building the house?
How much money could you easily free up monthly beyond that?

How much equity do you have for the house and land (excluding kitchen, furniture, and other reserves)?
What should the land cost (with/without acquisition costs)?

That way, the site can roughly cover the money side.

For the cost side, things like living space, house type, extras, floors, roof shape, energy standard, garage, basement, etc. already help.

I can help you with money:

Great, thanks!

How much cold rent are you currently paying?
around €550 flat rate including all additional costs (cold rent cannot be determined like this in our case)

What monthly savings contributions do you have that can/should be dropped when building the house?
around €415 in three building savings contracts

How much money could you additionally easily free up each month?
around €850 (€400 that we already set aside monthly anyway and have used in recent years to simulate the "saving situation," the rest through further restrictions, dropping car financing, etc.)

How much equity do you have for house and land (excluding kitchen, furniture, and other reserves)?
approx. €10,000 in cash assets
approx. €60,000 family support
approx. €15,000 saved in building savings contracts (does that count as equity or how is this applied in financing?)
A kitchen and some new furniture should also somehow be paid for.

What should the plot cost (with/without purchase costs)?
Depending on which plot is allocated to us, the land costs are approx. €100,000 - €120,000 purchase price (excluding incidental purchase costs)

For the cost side, things like help with:
Living area: 150-160 m² (according to owner’s estimate and comparison with existing houses of parents and friends etc.)
House type: 2-story single-family house with the possibility to later convert the upper floor into a separate apartment (staircase separable).
Floors: 2 + basement
Roof type: Gable roof/flat roof
Energy standard: Preferably as energy-efficient as possible. So far no major restrictions.
Garage: Double garage (planned entrance to the house)
Basement: yes (house with basement)

Additionally:

[*]Smart home
[*]2-3 children's rooms (possibly one in the basement with a light well)

[*]Living (of the parents) on one level (on the ground floor from the start possible)

Oh yes, one more thing: I am aware that it is quite possible that our (desired) expectations may not necessarily align with our financial capabilities. My concern is to bring the financial and construction planning aspects as close together as possible, and then to see whether the result is acceptable to us or not.

We hope that this year we will still be informed whether we get a place assigned or not.

Ouch, that sounds very much like a planned economy. "You will be placed"

Rough house prices can be given to you here for orientation,

Note house prices. What may come in terms of soil replacement or such jokes is different for every plot. So the famous "plus X".

Oh yes, one more thing: I realize that it is quite possible that our (desired) ideas are not necessarily compatible with our financial means.

It is not uncommon for there to be several rounds of courtship until the building wish and financing have found each other.

So: Think tank money

You will also have to pay additional costs in the house on top of the current warm rent. Let's say 250 euros... leaving 300.

Let's simply disregard the building society savings for calculation purposes. It helps with the math, even if reality might turn out a bit differently. You won't make huge profits or differences with it.

So:
300+415+850= 1565 = 18,800 annual annuity
With a 5% annuity (regardless of how interest and repayment are distributed) you come to about 375k financing.

375 loan
+10 cash
+60 family
+15 building society contract
=460,000 EUR

-10 additional purchase costs
-10 kitchen
-10 furniture and such
-40 additional construction costs
-120 land
=270,000 EUR
(No buffer included for surprises)

So if you want to plan solidly at the upper limit of what’s possible, I would calculate with a target price of the house of about 250,000 EUR (+-20,000 EUR).

That would give about 120 sqm in my think tank (2000 EUR/sqm, BW is unfortunately expensive). All this without a basement, without a garage, possibly with KFW55 included...

All values mentioned can still easily fluctuate by 10% because they are roughly calculated. But now you have an idea of how to roughly calculate.

Thank you for the breakdown...

So, if I carve out about €60,000 for the basement + garage, there would still be €200,000 left for a house (in whatever scope) and a buffer of €10,000... That allows for further planning...

Thank you very much!