Prefabricated house offer: Price realistic?

You can get that in the North for 200 without a garden and kitchen and so on.

I hadn’t considered inspection shafts, noted. Who decides where to put them and whether/how many shafts are needed? According to DW, the connection for rain gutters is prepared during the construction of the BP and is supposedly included in the price... I can’t really judge that again. Landfill costs – no idea without soil classification. The property is relatively large at 1100m2, definitely possible to store temporarily, and disposal... maybe distribute it on the property *cough*? Depends on the excavation material. Otherwise, I calculated: 2K for filler/painting, 2K for the interior doors (there are only four), for the 50m2 flooring (kitchen, bathroom, and hallway would already be tiled by DW) up to max. 50 EUR/m2. If possible, less. Tiles would be great, partly because of the underfloor heating. Under no circumstances do we want laminate or click vinyl or even carpet, rather a decent PVC floor suitable for underfloor heating with a wear class of 31/32 or so.

The drainage plan is probably done by someone from DW too? Definitely part of the submission plan. We needed two because the sewer system is separated into fresh and gray water. (Eckental, so somehow in the Erlangen catchment area as well.)
We also had this preparation for rain gutter drainage, but that was just about a meter from the house, the rest has to be paid separately.
Price-wise, you are definitely fine with the interior doors; filling and painting will probably be a bit more. Don’t even try mixing the Uniflott yourself, you’ll just frustrate yourself, better buy the Uniflott Finish. Costs more, but saves nerves and time. And you should definitely buy such a sander for about 100-150€.
Tiles are doable price-wise, but don’t forget you still need adhesive, tools, skirting boards, etc.

Do you have to pay for construction electricity yourselves?
Then another approx. 1000€ for having it + consumption (heating the screed = expensive)

So far you have not mentioned it, but I assume you are planning with a ventilation system?

Regarding solar system:

I currently do not know how a photovoltaic system is recognized as an alternative to the solar system in terms of the Energy Saving Ordinance in combination with the gas heating. But:

Solar system ~ 6000€: produces hot water until the hot water storage tank with 190 liters is full and is a renewable energy source.

Photovoltaic system ~ 6000€ - XY€: produces electricity which you can use for hot water and/or heating energy if you want. Additionally, you get money back for the unused energy thanks to feed-in.

Maybe your house, if it is currently planned as a KFW 55 house and has a good orientation, can even shift towards KFW 40 with a photovoltaic system? Maybe the 10,000€ instead of 5,000€ repayment bonus is welcome if the KFW funding is interesting for you?

And if you are planning underfloor heating anyway, at least have it planned to be heat pump compatible.

I personally would also rather not prefer a bungalow, if only because of the required floor area, but my wife is mobility impaired – so it should definitely be as barrier-free as possible. Stairs wouldn’t be so good, so multi-storey houses are out. So, she doesn’t need a wheelchair, but climbing stairs isn’t so great in the long run.

I don’t know what you’re reading into this, but certainly nothing I wrote. I like bungalows, though not for families of four, because I think somewhat ecologically, but otherwise gladly. However, then please no 70 sqm for living, but 120 or so. If your wife is mobility impaired or nearly so, then please plan a house with low barriers or barrier-free, but you won’t get that from Danwood, at least not with Family-Line. I also find it completely fine to plan somewhat more sparingly. However, you can also overdo it in terms of equipment, although the focus here is probably on reasonable equipment for your wife. Whether strap or crank doesn’t matter here (I have straps, by the way, because I was also a frugal home builder), but in your situation, I would clearly want something electric for example. And building technology should be right, don’t skimp! By the way, there is really enough info and tips on incidental construction costs in the forum, just use the search. Also about Danwood.