Semi-detached house, 2.5 stories, with basement, 3 apartments

[*]Plot 12 m wide and approx. 50 m deep
[*]the street side of the house faces almost exactly southwest, so the garden is located in the northeast
[*]street is moderately busy (I estimate about a thousand including buses – it is the "access road" to the neighboring district, but there are plenty of times when you can cross the street with your eyes closed)
[*]on the plot there used to be a 2.5-story semi-detached house docked to the neighboring house with approx. 7 m depth (I would guess from the 1950s), which – like the neighboring house – was later extended with a 2-story annex, whereby on "my" plot the annex was about 1.5 m lower than the neighbor’s and was additionally extended on the right side
[*]the neighboring building is on the left, roughly northwest
[*]on the "free" house side (south; seen from the street on the right) there is a residential building (~10 m high) with only about 1.7 m distance to the property boundary, thus shading the southeastern gable wall of my house in winter
[*]the original 7-m house had a basement, the annexes did not
[*]the house stood vacant for a long time and was therefore demolished by the current owner of the plot (basement filled with construction debris, floor slab still existing but of course no longer usable)
[*]distance from the facade to the street approx. 4.7 m
[*]street rises from left to right (when looking at the house) by about 1.2 m
[*]level of the upper edge of the basement ceiling of the old house was about 1.4 m above the lowest point of the street
[*]there is no development plan, so I only have to orient myself towards the neighboring buildings and the general building regulations (RLP)
[*]if I follow the old building structure on the plot, I can (and want to) build a semi-detached house with 9 m width and 11.5 m depth on the plot and theoretically extend it by up to 5 m on the "free" house side (3 m is "enough" for me)
[*]in particular, I have to orient the roof pitch on the street side to the neighbor’s house (approx. 41°), but I can also make the roof higher and the house 1.5 m longer / deeper than the neighbor’s as before (there are similar examples in the immediate neighborhood, I have also already shown the plans to the responsible official at the building authority and he saw no problems)
[*](the thick column visible on the left side of the house in the screenshot holds cables from which a lantern hangs over the street)

Planned is a KfW-40-qng house for rental with

[*]approx. 45-50 m² basement apartment, the rest as technical and storage room, entrance on the left side of the street
[*]preferably age-appropriate / barrier-free apartment on the ground floor (approx. 90-95 m²), entrance also from the street side
[*]the ground floor has an approx. 3 x 5 m extension toward the garden (northeast), which is used as a balcony on the upper floor
[*]possibly the walls between kitchen/living room on the ground floor can also be removed, which might be better regarding barrier-freedom
[*]a two-story apartment on the upper floor + attic with approx. 77 m² each minus roof slopes; separate entrance via an external staircase at the (side) gable wall
[*]special feature on the upper floor: the guest WC is located under the stairs (I also know an apartment where it was under a roof slope at 1.5 m height – which worked without problems there, so it should be possible here too, although footstep noise might be disturbing)
[*]roof pitch on the street side (on the plans left): approx. 41°, on the garden side with 1.2 m knee wall (possibly more) approx. 25°
[*]in the floor plan I have drawn the rather thick exterior walls of my passive house with 473 mm, thinner and thus larger rooms are always easier, the other way around as well
[*]door widths are generally set at 90 cm (primarily for barrier-freedom on the ground floor)
[*]whether the extension in the basement is underpinned or only gets a cantilevered floor slab depends on budget and QNG calculation
[*]the windows / furniture are only roughly drawn

The planning was done by myself (created using SketchUp, the terrain modeling in the program is somewhat difficult, so please do not complain about the stairs hanging in the air). I have tried to make the best possible use of the areas, even though the two L-shaped rooms in the upper floor/attic slightly bother me (on the other hand, my childhood room looked similar).

The state building code RLP says that a building with 3 residential units can sensibly be assigned to building class 2 (instead of 3) if it is on a slope (I hope that the 1.2 m lateral and/or 1.4 m from the street are enough for this definition) and the lowest apartment has a separate exit (besides the space-saving effect, one of the reasons why I rely on separate entrances / external stairs).

What is the parking space planning like? With 3 apartments, you will need several parking spaces.

A car fits crosswise in front of the house, if necessary also two small cars lengthwise (they are just 4.7 m).

In the back garden area I wanted to build a double carport, even if it doesn’t necessarily look nice, it can’t be helped because the street distance etc. is all predetermined.

In addition, 2 cars can park along the street, no idea to what extent that counts in a "developed old residential area" (incorporated village).

Somewhere I also think I once read that you can rent the basement granny flat explicitly without a parking space (the bus stop is only 50 m away).

There is a car parked crosswise in front of the house,

Then I’ll ask differently: what does the parking space ordinance say about the number of parking spaces per residential unit? Usually such a project fails simply because there is no space for it,

[*]Plot 12 m wide and about 50 m deep
[*]the street side of the house faces almost exactly southwest, so the garden is in the northeast
[*]the street is moderately busy (I estimate about a thousand including buses – it is the “access road” to the neighboring district, but there are plenty of times when you can cross the street with your eyes closed)
[*]on the plot stood a 2.5-story semi-detached house “docked” to the neighboring house with about 7 m depth (I would guess from the 1950s), which – like the neighboring house – was later provided with a 2-story extension, whereby on “my” plot the extension was about 1.5 m lower than that of the neighbor and was extended further on the right
[*]the neighboring building is on the left, roughly northwest
[*]on the “free” side of the house (south; seen from the street on the right) there is a residential building (~10 m high) with only about 1.7 m setback from the property line, therefore it casts a shadow on the southeastern gable wall of my house in winter

Could you please show a readable site plan, even a self-drawn one, with the whole setup? A picture says more than a thousand words. Also, the floor plans are not exactly self-explanatory. Tip for planning: washbasins also need space in bathrooms, wardrobes are at least 60 cm wide in planning. And please engage with the subject of barrier-free design – on the ground floor you can’t get through the door and hallway with a wheelchair at all.

According to the current parking space regulations (thanks for the search term), I need 3 parking spaces, which can be reduced by 1/3 to 2 depending on the area zone due to the public transport connection (but I can only check this tomorrow, the geoportal where I can determine the area zone is currently not working). Alternatively, I might have to pay a buyout sum of about 4,000 EUR to the city if the construction of parking spaces is not possible. Additionally, I need 5-6 bicycle parking spaces, which I can offer in the basement or alternatively at the carport. Theoretically, I could forgo 1/4 of the car parking spaces with 4 additional bicycle parking spaces, but with only 3 parking spaces, this will (probably) not be possible.
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I have attached an aerial photo on which the old, demolished house is still standing. The trees on the property have been completely removed (except in the not visible rear part of the garden, but that is irrelevant for the house construction). The new house will have roughly the same dimensions, only the extension at the back right will be shorter.

I have also attached a site plan from the geoportal, on which I have colored the areas that are no longer or additionally built over.
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Regarding accessibility, I agree with you, the corridor would have to be 21.5 cm wider (1.5 m instead of 1.285 m), alternatively 1.2 m width is sufficient if there is a turning area of 1.5x1.5 which I could reach if I widen the kitchen door area by 30 cm (then it’s just an L-shaped kitchen instead of a failed U-shaped kitchen). Or alternatively, I could design the living/cooking/dining area + corridor completely open, i.e. omit the two doors plus sliding door and the little wall in between.

I actually planned the proper cabinets with 60 cm depth, bookshelves or similar sometimes a bit slimmer. The specific furnishings are ultimately the tenant’s business anyway, I don’t know if they happen to have a wall unit from great-grandpa or refurnish at Ikea or just have a big chest of drawers :-). So the furniture is only place holders so that one can see that it is somehow possible.

Regarding the washbasins you are right, I was too lazy to draw them in. Since I’m not planning luxury apartments, these will probably only be simple washbasins (i.e. not those modern 3-meter wide double washbasins or similar "frills"), so the free space in the bathroom should be sufficient for that.

PS: another screenshot from SketchUp from a bird's-eye view from the west (this shows the ensemble best). Please note that the roof overhangs are drawn at about 1 m

You can change the perspective by pressing the mouse wheel (I would not recommend this for the floor plan), zooming is also possible with the mouse wheel, if you press H, you can then move the map/plan left/right/down/up with the left mouse button.