ᐅ Building Site: Extensive Fill or Is It Better to Have a Basement with Excavation?
Created on: 31 Mar 2019 19:14
T
Thierse
We own a sloped plot (about 3 m (10 ft) height difference between the street and the future garden level at the basement) and originally planned to build with a residential basement because the land slopes downward from the street.
However, today we visited the site with an experienced civil engineer who specializes in foundations for prefabricated houses. He believes it would be more practical and cost-effective to build without a basement and instead raise the ground level by up to 3 m (10 ft) using recycled gravel. Even if that requires around 500 m³ of gravel.
This could be well compacted with a roller, and settlement would not be an issue. The parking spaces and the house facade would need to be filled in anyway to reach the entrance.
Otherwise, due to the relatively high position of the sewer connection, we would need a pump system in the basement, and disposing of the excavated material (clay soil, about 200 m³) would be very expensive in the region because there are almost no landfills available (35 €/m²).
Who has experience with these issues? I thought a basement was usually more cost-effective and safer on sloped plots than large-scale fill?
However, today we visited the site with an experienced civil engineer who specializes in foundations for prefabricated houses. He believes it would be more practical and cost-effective to build without a basement and instead raise the ground level by up to 3 m (10 ft) using recycled gravel. Even if that requires around 500 m³ of gravel.
This could be well compacted with a roller, and settlement would not be an issue. The parking spaces and the house facade would need to be filled in anyway to reach the entrance.
Otherwise, due to the relatively high position of the sewer connection, we would need a pump system in the basement, and disposing of the excavated material (clay soil, about 200 m³) would be very expensive in the region because there are almost no landfills available (35 €/m²).
Who has experience with these issues? I thought a basement was usually more cost-effective and safer on sloped plots than large-scale fill?
I would also recommend commissioning a chemical soil analysis. We had Z1.1 soil, as the arsenic content was slightly exceeded, and we paid about €42 per cubic meter for disposal. We were somewhat lucky and were able to reuse the soil on the A8 construction site; otherwise, the costs would have been even higher.
We are building in the Rhein-Neckar district. The landfills charge 25 €/m3 (about $27 per cubic yard) for uncontaminated soil. On top of that, there is transportation. So the mentioned 35 € (about $38) doesn’t seem that unrealistic to me.
However, I have concerns about stability and settlement when filling with gravel up to 3m (10 feet) high. Can it really be done that well?
On the other hand, I could do without a lifting system. How much does it cost to install a fully functional bathroom in the basement?
However, I have concerns about stability and settlement when filling with gravel up to 3m (10 feet) high. Can it really be done that well?
On the other hand, I could do without a lifting system. How much does it cost to install a fully functional bathroom in the basement?
Thierse schrieb:
I could do without a sewage lifting station, though. How much does it cost to install a fully functional bathroom in the basement?Hello ThierseYou might as well ask how much a car costs.
A standard bathroom, including sink and shower, fully tiled, can get quite expensive if you hire a premium company. If you’re willing to get your hands dirty and hire a versatile tiler, you can keep costs under 1,000 euros plus materials.
Thierse schrieb:
The landfills charge 25 €/m3 (about 7 cubic yards) for uncontaminated soil. Here lies the catch.
What exactly counts as uncontaminated? I recently experienced this myself. We filled a container with 7.5m³ (about 9.8 cubic yards) of excavated soil. As soon as the landfill worker saw one or two stones, suddenly it was classified in a higher category with increased fees. The difference was only around 30 to 40 euros.
Steven