Multi-generational house with underground garage for 3 families

What I can see emerging here is, in character, a fairly ordinary three-family rental building with the only differences being that there are no strangers in the residential community and likewise no stranger as a landlord. But in layout, it will ultimately be the same form of housing.

We initially threw the underground garage plan into the discussion since for two new buildings in the neighborhood (plot 1 approx. 890 sqm / plot 2 approx. 1100 sqm) an underground garage was built in each case...

They would then be interesting to examine more closely to see how it was solved there. It has already been some (>10) years since I last dealt intensively with underground garages. If you fully exploit the simplifications for small installations, they are inconvenient to use. Don’t forget: a Pyrrhic victory is not a trivial skirmish, but even more inefficient than that.

Can you cheat around the underground garage by building a car elevator like that?

Double parkers are also no cost-saving solution, only in terms of space consumption are they significantly cheaper. Figuratively, they are like a repair platform with two tow truck beds and a shaft each. You can style them somewhat elegantly, but then money really must not be an issue.

I would most likely consider an ensemble as three single garages in a row, three parking spaces, and a bike and bin box. In my opinion, that fits best for a possible later sale to someone who acquires it classically as a multi-family house for unrelated parties — if you don’t even plan the layout from the start as three individual condominiums.

What I see potentially emerging here is, in character, a fairly ordinary three-family rental house with the only differences being that there are no strangers in the house community and likewise no stranger as landlord. But in layout, it will ultimately be the same form of residence.

Perhaps I have the wrong expectations here, but in my assessment, a good architectural firm should and must have the ability to create something significantly more attractive instead of a fairly ordinary three-family rental house, for example?

and . We initially threw the plan for the underground garage into the room because with two new buildings in the neighborhood (plot 1 approx. 890 sqm / plot 2 approx. 1100 sqm), an underground garage was each built...

Basically, I think underground garages are great (if the budget allows). The size definition, as far as I can tell from the Bavarian GaStellV, is independent of whether it is purely private use or not. The usable area counts as parking space area + traffic area. Up to 100 sqm, the access can be built however you like; this corresponds to an underground garage with 4 to 5 parking spaces.

By the way, 1000 sqm for a semi-detached house with a granny flat seems almost princely to me for Munich. I've already heard of semi-detached house plots of 150 sqm with 90 sqm of built-over area through the house.

A good architecture firm should and ought to have the ability to create something significantly more attractive instead of a rather ordinary three-family rental house, right?

I did not say that it had to look loveless. But as Yvonne already pointed out, loosely arranging and sprucing up reaches its limits in a building plot that is still only 14 m "wide" after setback distances.

As much as I, as a retiree in the distant future, would wish for a beautiful penthouse with a roof terrace (without a garden that I have to maintain), I believe that the necessary 3rd stairwell (escape route!) + elevator is a bit too much (space requirements, costs). Maybe a good architect can design a plan with a house in a slightly L-shape (see sketch) that separates the two residential units a bit better than a classic semi-detached house (to avoid conflicts) and better accommodates individual wishes in the floor plan than a mirrored design. With a building window width of 14m and presumably about 200m2 of floor space needed for the house (I assume 2.5 floors), this results in a quasi-square building. Stretched a bit lengthwise, there should be some creative design possibilities.

As much as I would wish for a nice penthouse with a roof terrace (without a garden I have to maintain) as a retiree in the distant future, I believe that the necessary 3rd stairwell (escape route!) + elevator is a bit too much here

I think a "penthouse" here can only mean a top-floor apartment extending over two adjacent maisonettes - not a bungalow "on a flat roof as a plot".