Feedback floor plan - size and price ok?

Please let go of this plan, don’t try to cut corners somewhere, that simply will never suffice.

Cancel the granny flat! Really, just do it. You’re welcome, you’ll thank me.
As has already been aptly said here: 10-year-old son... 15-20 sqm is more than enough, he doesn’t need his own apartment within the apartment?! It’s well intended, but then he wants to study in Hamburg or MUC at 20, and then? Renting it out, as mentioned, is no panacea, please read up on the subject.

Make a new floor plan and others might help as well. They do it great, at least providing food for thought...
Basement with living/kitchen/dining facing the terrace, the technical rooms on the hillside side, upstairs the bedrooms and bathroom, that’s roughly how I’d start.

Has a structural engineer already given their input?
They can add another five-figure amount. That was the case for us, and that with soil class 5-6.

20k for the outdoor area is enough for grass seed, driveway, front garden, terrace, and a bit of greenery on a flat plot with own labor.
I believe we've already spent over 6k on earthworks in the last 2 years, and filling and compacting the driveway must have been around 5k as well.
30k for the garage in the hillside is not enough. I would rather expect 50k.

How I would split it, I have already written. Definitely plan a stair-free access to the garden. Wheelbarrows and sack trucks make life much easier.

Not the first time here that the architects completely run wild with their proposals. My respect for the freelancers is now buried somewhere in the basement. Of course, we are mainly presented with problem cases here in the forum. Nevertheless, I am appalled. If the client now naively scrapes together the money and presses "Start," he may be ruined. And the architect knows that exactly. Pure greed for profit. This is an outrageous impertinence. Just for this breach of trust, I would immediately terminate everything with him.

I wouldn't assume any bad intentions there. Well-known architects from our area renovated an old farmstead and completely underestimated the costs... Inexperience.

So for me, 500,000 including ancillary building costs and high-quality fittings were enough.

- 200 sqm living space
- solid construction
- no basement
- 2 full floors
- hipped roof
- including a brick carport for 33k
- in Central Hesse
- own work: 0

the whole thing on a plot with a height difference of 2.8m over 29m

So dear forum, thanks again for the many feedbacks and ideas. As already mentioned, I think we need to go over 'Los' again. Everything else would be unwise. I stayed up late last night designing (Sweet Home 3D). So far, nothing presentable has come out of it. If there is interest, I would keep you updated... Best regards The Johann