Floor plan of a single-family house with an optional granny flat

The disadvantages are the same as when you live in an apartment. Or are you thinking of other issues? The advantage of the option is that, for example, if there is financial distress, I can see it as a personal security and maybe sleep better. Like an insurance.

If you were to follow the idea that led to this very poor floor plan: It should be possible to separate it into two residential units. What would you do differently to improve the floor plan a bit?

The typical two-family house has become relatively uninteresting lately because people don’t like living under the same roof with landlords. Even vacation apartments with landlords together are unpleasant.

550.000

Due to the small remaining garden area, I would like a rooftop terrace,

Building height up to parapet 6.5m and then another 3.5m.

1 parking space required

With granny flat 2 parking spaces is correct.

The closet does not have to be in the room, but it probably looks stupid if there is only a bed in this room.

I am currently annoyed that the hallway on the ground floor is, in my opinion, not well used and wastes unnecessary space.

Home office or bedroom on ground floor

The ground floor and upper floor should therefore be decoupled in terms of noise. An open kitchen would be nice because I want visual space;

Ideally, the kitchen could be separated if necessary, for example with a sliding door, so a double sliding door would be great, but I don’t think that is included in the current floor plan.

The ground floor should be convertible to barrier-free if necessary, thus a larger shower, accessible washbasin, wider doors,

Full bathroom including washing machine, because of granny flat.

so that the tenant doesn't have to drink his beer on the hood of his car in front of your [Baufenster] in the evening.

Regarding the draft:

€550,000 is enough for construction costs of €50,000 and for just under 170 sqm of living space in the house. No more. The outdoor facilities come on top, the basement is also not priced in. Then two bay windows, sanitary/sauna in the basement, roof terrace, costs arising from a household separation, i.e. pre-installations—this is all not feasible price-wise.

Then additional water pipes, irrigation, stairwell to the roof terrace, increased load-bearing capacity, etc.

And with that, the stairwell at the corner of the house is not compatible anyway. It would have to be within the building footprint so that the stairwell to the roof terrace is not on the attic side.

Exactly! Where are those now? Where is the parking space for the tenant, which may only be paved later but should already be planned now? -> Consider privacy in the floor plan and usable areas on the property. None of that can be seen in your planning. Not thought through at all, still not mature for internal acceptance of the plan.

No idea what is meant by the box, but where a sleeping area is planned, a wardrobe might also be necessary.

You planned that unnecessary open space in front of the bathroom and the office. It is a bustling cloakroom and play area in one.

It's original, of course, to plan the office exactly where the house is probably loudest. You do not only talk about quietness, but also here:

.. with decoupling of floors due to noise. An open kitchen is also loud. Your planning contradicts your needs for quiet. The visibly open access to the toilet was already mentioned. What about separation into two residential units? Is a partner then not allowed to have visitors because there is no private retreat for the other? Lots of space but no possibility to retreat.

So what now? Bay window or sliding door? The needs contradict each other („ideal“, „would be nice“, „important is..“) in this floor plan, mind you!

It IS NOT barrier-free. It is also not barrier-ARM, as there is no storage room within reach. The kitchen is not barrier-free. A bathroom with 2 meters width and a washing machine inside is terribly tight if you don't know where to put crutches or other bulkier walking aids.

A fully functional apartment has a storage room, a possibility to dry laundry, and if possible, a terrace so the tenant does not have to drink their beer on their car hood in front of your bathroom window in the evening. Then the small target group as tenants is also admitted a basement room without having to access the storage rooms through the freezer room.

For use of the upper floor as a family flat, at least for now, the rooms are very disadvantageous in their varying sizes. Basically, 5 sqm should be aimed for a shower restroom if it is the second bathroom. 6-something sqm is already quite sparse for a main bathroom, especially if laundry is also done there. Where laundry is done, space is also needed for sorting and ironing. For 4 people, I consider such a bathroom inadequate or insufficient, especially considering that you control the decision yourself and this is not a 60 sqm social housing unit. A bay window can be appealing, even in a kitchen. But definitely not in a rather small and compact kitchen where you don't know where to put things because there are no tall cabinets for storage. It remains a restless place that does not invite you to sit and dream. The window seat will probably be used more as a shelf.

Orientations are not thought through, neither inside the house nor between the two residential units in relation to each other. All in all, ready for the round file!