Massive house costs KFW 70 - Prefabricated house

Hello everyone,

we are planning to build.
Now some say it is no problem if you build a semi-detached house and the roofs adjoin each other. Here you simply put metal sheets under the roof tiles in case snow accumulates. Other construction companies say again that you can definitely not build like this / this is no longer how you build today. What do you say about that? Especially, what do you think the district office will say about it? Will it even be approved? (see picture)

I would also be interested in how high you estimate the construction costs?
What is generally cheaper? Solid house or prefabricated house?

Basement with granny flat (self-finished) 45,000 EUR
KFW 70 - prefabricated house 200,000 EUR with heat pump and ventilation system
Additional construction costs 30,000 EUR

How much would it cost us as a solid house? House dimensions 8.5m by 11m
Knee wall 1m?

I would be very grateful for your opinions before I have long conversations with architects again and then don’t get an offer because there is still some point open.

more pictures

Basement with granny flat (self-conversion) 45,000 Eur KFW 70 - prefabricated house 200,000 Eur with heat pump and ventilation system Additional construction costs 30,000 Eur

With or without land?

With or without property?

without property. That belongs to my mother and aunt

Price sounds relatively reasonable at first... without knowing more about the equipment etc., not much more can be said...

How large should the living space (without the [Einliegerwohnung im Keller]) be? ~140-150m²?

In terms of price, prefabricated construction and solid construction should not differ much.

ah ok thanks good to know, because we probably want to build a prefab house. And I had heard from someone that solid construction is cheaper.....that made me uncertain.

What do you think about the roof? Would you build it like that? I just thought otherwise it would be really bad for the light if only one gable opening faces north and dormers are also forbidden :-(