Idea not feasible due to residential basement?

Hello Jan,

[*]The parents are supposed to move into the basement and get a living area of 80sqm. Another 10 sqm are planned as utility space (technical room, storage room)
[*]On top of that, as mentioned, a 1.5-storey single-family house with about 120sqm

How is the basement supposed to have over 90 sqm of floor space if the ground floor above it only has 65 sqm?

[*]The basement is supposed to protrude a bit to the south (towards the slope) to offer the ground floor a small terrace.

Aha – expensive issue, because the terrace can hardly be that "small" (missing sqm of the granny flat); on the other hand, small is relative.

oh yes: Both in prefabricated construction. Due to various circumstances, the rather fixed or plannable time frames of "when everything will be ready" are important to all of us.

Currently, a solidly built single-family house is ready for occupancy faster than the building shell of the prefab house is erected.

It was planned a budget for the house of 300 to 350 thousand euros. Not turnkey, but each as "almost finished". Do flooring yourself, walls, etc. ... We have already received two first offers ... in both the basement accounted for about 60k €, to which the costs for the living basement were added. These were about 120 to 140 thousand euros! Oof!
In the end, both offers were at least 420 thousand, whereby in the second offer the "5 in front" was also mentioned if certain cases occurred.

Did we misjudge it so much with our 300-350k € (for the house)? Should one say here that something like this simply isn’t feasible with the mentioned requirements?

Except for a few exceptions, customers of prefab house providers buy the basement externally. If I now look at what you have planned for the living basement, I would guess that the number will cost you about TEUR 100 - 120. Including the protruding basement, terrace system, exterior plastering of exposed masonry and protection against rising damp and seepage water and construction as a granny flat. Plus another TEUR 195 for the single-family house (prefab houses tend to be more expensive), plus additional construction costs, plus painter/flooring work in DIY, plus finished garage, plus outdoor facilities, plus reserves for extras. It will be at least TEUR 400.

Thanks for your feedback so far!
For cost reasons, we could also back out of this and just add a normal balcony.

The exciting question remains, where you want to conjure the missing 25 sqm for the granny flat in the living basement from?

Rhenish regards

Since we are planning something similar next year, I am also a bit surprised. I thought a basement in a hillside location would be cheaper than the living space in the upper floors.

Wrong thought! With a hillside location, it does make sense to expand the cellar - alternatively, you sink a lot of money into embankment - but this number is not cheap nevertheless. Rhine regards

80m² living space plus 10m² utility space downstairs plus 120m² living space upstairs equals 210m²

Calculated at 1700 euros per m², you are at 357,000 euros without the usual additional costs.

Why does everyone actually think that a basement is cheaper than above-ground living space? What does a living basement require less of? I would say it actually needs more (waterproofing, earthworks, etc.). Or should my house become cheaper if I have it covered with earth?

No, the construction expert has understood it completely correctly: 80 granny flat +10 basement + 90 ground floor + 60 attic Makes a total of 240 sqm livable and heated

Why does everyone actually think that a basement is cheaper than above-ground living space?

Maybe because building upwards is more strictly regulated and usually limited. If you also plan for the parents, you usually don't want to put them in the attic.

Of course, there are good concepts: two housing units side by side on the ground floor and the attic for the builders themselves.

The exciting question remains where you’re going to conjure up the missing 25 sqm for the granny flat in the residential basement from?

Well, if you only knew!
No, the 120 sqm are our minimum requirements. Roughly estimated, we thought of an external width of about 10m to provide the parents with a minimum width of window area. As I said: We’re just at the very beginning and want to see now where the journey can go, what is feasible.

[...]plus finished garage, plus outdoor facilities, plus reserves, plus extras. It will be at least TEUR 400.

Once again here: The mentioned budget was only allocated for the house (including basement). Without garage, without outdoor facilities, without reserves, without extras! That doesn’t mean these items aren’t on the radar (within the planned total budget).

Oh, I almost forgot:

Currently, a solidly built single-family house is ready to move into faster than the shell of a prefab house is erected

Here I didn’t mean the entire construction time, but individual dates (2 to 4 days) on which a prefab house + basement can be “ready” and standing.