Hello everyone,
As mentioned above, this is currently the main question for us. I’m sure it has been asked many times before, but every construction project needs to be considered individually.
My wife inherited the plot of land from her parents.
Information about the plot:
- not yet developed
- 900m² (9,688 ft²) area
- street at the property has about a 3% slope
- the plot has the same slope where it borders the street
- the plot is located about 1.2 meters (4 feet) below street level on the north side (street side)
- the land rises towards the south/back, reaching street level towards the southeast and almost towards the southwest
- the sewer line is about 1.5 meters (5 feet) below street level
- approx. 60 meters (197 feet) west is the nearest intersection with electricity, water, and possibly sewer connection (more on this below)
- a 3-chamber septic tank is required WITHOUT a treatment pond. The pond is centrally located for the village
We have already had a soil inspection performed with two small percussion boreholes:
- Borehole one near the street at the lowest point: after 1.4 meters (4.6 feet) below the turf is buildable ground. Seasonal groundwater pressure starts at 0.9 meters (3 feet). So, 1.4m + 1.2m = 2.6 meters (8.5 feet) below street level is solid ground.
- Borehole two roughly in the middle of the plot: after 2 meters (6.6 feet) below the turf is buildable ground. Groundwater at 2.9 meters (9.5 feet). So, 2m + 0.7m = 2.7 meters (8.9 feet) below street level is solid ground.
In addition, we took some important height measurements, which allowed me to include the figures mentioned above.
The house floor plan would be about 40m² (430 ft²) larger if built without a basement. We would probably also need a garden shed or similar for the lawnmower, patio furniture, etc.
This would not be necessary if a basement is built.
A garage will also be built, but it will have a car lift, so it’s not suitable for storage.
The basement would ideally be a waterproof concrete box ('white tank') with appropriate insulation against cold.
Our estimate is that the basement would cost about 30,000 to 40,000 euros more.
What do you think?
Does having a basement make sense?
How much would you estimate the cost difference to be? (With and without basement)
Is it mandatory to install a sewage lift station with a backflow preventer? Or would it be possible to route the wastewater after the septic tank to the intersection in the west, so that a natural slope and height difference could be used?
What worries me most is the issue of wastewater and moisture in the soil and the associated additional costs.
Drainage, possibly a lift station.
Or should the 3-chamber septic tank be placed so deep that a natural slope is created?
How steep would the slope between the house outlet and the septic tank need to be?
The neighboring plots will almost certainly not be built on, so using them for excavator work should not be a problem.
I hope I haven’t forgotten anything.
Thanks in advance,
Joergi
As mentioned above, this is currently the main question for us. I’m sure it has been asked many times before, but every construction project needs to be considered individually.
My wife inherited the plot of land from her parents.
Information about the plot:
- not yet developed
- 900m² (9,688 ft²) area
- street at the property has about a 3% slope
- the plot has the same slope where it borders the street
- the plot is located about 1.2 meters (4 feet) below street level on the north side (street side)
- the land rises towards the south/back, reaching street level towards the southeast and almost towards the southwest
- the sewer line is about 1.5 meters (5 feet) below street level
- approx. 60 meters (197 feet) west is the nearest intersection with electricity, water, and possibly sewer connection (more on this below)
- a 3-chamber septic tank is required WITHOUT a treatment pond. The pond is centrally located for the village
We have already had a soil inspection performed with two small percussion boreholes:
- Borehole one near the street at the lowest point: after 1.4 meters (4.6 feet) below the turf is buildable ground. Seasonal groundwater pressure starts at 0.9 meters (3 feet). So, 1.4m + 1.2m = 2.6 meters (8.5 feet) below street level is solid ground.
- Borehole two roughly in the middle of the plot: after 2 meters (6.6 feet) below the turf is buildable ground. Groundwater at 2.9 meters (9.5 feet). So, 2m + 0.7m = 2.7 meters (8.9 feet) below street level is solid ground.
In addition, we took some important height measurements, which allowed me to include the figures mentioned above.
The house floor plan would be about 40m² (430 ft²) larger if built without a basement. We would probably also need a garden shed or similar for the lawnmower, patio furniture, etc.
This would not be necessary if a basement is built.
A garage will also be built, but it will have a car lift, so it’s not suitable for storage.
The basement would ideally be a waterproof concrete box ('white tank') with appropriate insulation against cold.
Our estimate is that the basement would cost about 30,000 to 40,000 euros more.
What do you think?
Does having a basement make sense?
How much would you estimate the cost difference to be? (With and without basement)
Is it mandatory to install a sewage lift station with a backflow preventer? Or would it be possible to route the wastewater after the septic tank to the intersection in the west, so that a natural slope and height difference could be used?
What worries me most is the issue of wastewater and moisture in the soil and the associated additional costs.
Drainage, possibly a lift station.
Or should the 3-chamber septic tank be placed so deep that a natural slope is created?
How steep would the slope between the house outlet and the septic tank need to be?
The neighboring plots will almost certainly not be built on, so using them for excavator work should not be a problem.
I hope I haven’t forgotten anything.
Thanks in advance,
Joergi
N
nordanney9 Apr 2026 22:07A proper basement? No, there’s no slope, just poor soil.
You would need to know the site better to say more.
You would need to know the site better to say more.
N
nordanney10 Apr 2026 07:58Complete site plan including elevations and house design.
M
MachsSelbst10 Apr 2026 09:03Is this really such a big deal?
We and a few neighbors have done the same. Here, the soil was replaced up to 1 meter (3.3 feet), and for the remaining depth, strip footings were dug and directly filled with lean concrete.
Then gravel was added, compacted, and the frost skirt (frost protection layer) was poured on top of that.
It cost 25,000 EUR, excluding the slab, in early 2022.
It has been standing for almost 4 years.
We and a few neighbors have done the same. Here, the soil was replaced up to 1 meter (3.3 feet), and for the remaining depth, strip footings were dug and directly filled with lean concrete.
Then gravel was added, compacted, and the frost skirt (frost protection layer) was poured on top of that.
It cost 25,000 EUR, excluding the slab, in early 2022.
It has been standing for almost 4 years.
H
hanghaus202311 Apr 2026 07:07Basement with waterproof concrete shell approximately 100k. Site development 60k; if it becomes a residential basement, you can estimate around 4k per m2 (4k per 10.76 ft2).
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