Plot for new house construction with basement on a slope - construction costs?

Hello,

I am new here and have a few questions right away

Slowly the desire to have our own house is growing.

We have inherited a plot of land (an old house is still on it and needs to be demolished), which, however, has a steep slope. The dimensions are about 30m x 15m with a height difference of 4-5m on the shorter side (estimated). In addition, we live in BW in an earthquake-prone area.

The house is supposed to be about 12x10m in size. A basement is mandatory, which is probably also advisable given the slope.

We would be interested to know what construction costs one can roughly expect. And whether it even makes sense or is possible to build new houses on such a "steep" slope. Otherwise, we would have to look for another plot, but plots are rather scarce in this area.

Best regards

So you really have to like it – we are deliberately building on a slope because we like the plot along with the view so much. Together with the architect, we have positioned the house so that in the end we will only have about 550m3 of excavation – this can also be transported away in the municipality for €6.50 per m3. In general, everything can be built on, no matter how steep – it is always a question of money. Especially with a hillside plot, a standard house would be a waste, as there are really great opportunities here to "combine" the plot and the house.

But if you have to tear it down anyway, maybe the foundation is still intact. Or should the house be positioned in another location?

No, the house is supposed to be built in the same location, even if somewhat smaller. The old one is over 15m long. (altes Bauernhaus mit Stall) The question is whether you are allowed to build the new one so close to the property boundary again?

For a new permit, in my opinion, you must comply with the current legal regulations – including the currently valid setback areas.

Therefore, first inform yourself about which building regulations (development plan, integration requirement?) you need to observe in order to get an idea of your future house.

With a plot width of about 15 m, only about 9 m of external width remains for the house with 2x3 m setback areas. That is quite feasible but does not make a sensible interior layout easier, especially if you want to plan without an architect (and is somewhat far from your desired dimensions of 10x12 m ).

No, the house is supposed to be built in the same location, even if somewhat smaller.

I would benevolently consider reusing the basement entirely or in parts, as far as it is still usable.

Additional costs would initially possibly be increased safeguards and additional time expenditure, because the excavator has to work more "cautiously," as you say, since it is very steep.

Excavation is unnecessary if there is already a house with a basement there, right?
Can't you keep the basement and waterproof it anew?
Otherwise, the amount of excavation is less than with a flat plot; well, about half of the volume is above ground.

We use the excavation on our slope to fill in a terrace in the upper area.
Although partially retaining walls made of concrete and gravel coverings have to be used, so only part of the excavation can be used directly in the terrace area. The rest of the excavation creates a small meadow plateau.

If the house is supposed to be smaller anyway, you would also have enough space for a cavity wall with mineral insulation instead of classical Styrofoam insulation when keeping the basement. The outer shell could be built and plastered, or the outer shell could be brick.

Many costs can also arise from further garden design.
With us, many construction companies and architects calculated a lump sum surcharge of up to €50,000 for "additional earthworks due to hillside location."
I think they were not particularly familiar with hillside locations and estimated a lot of risk.
But we also found construction companies that saw no problems there at all and did not estimate a surcharge.
However, we also had to visit very many providers for that.