Hello everyone,
this is about a single-family house project with a basement (solid construction). During the soil test, groundwater was found at a depth of 1.30 meters (4 feet 3 inches) – now our builder says the construction could cost €200,000 more due to the need for a waterproof concrete shell (“white tank”), pumping, sheet piling, etc. Can anyone share their experience with this? Is groundwater really such a costly issue? We have a meeting with our builder on Tuesday, but we would be interested in hearing your experiences beforehand.
Best regards
this is about a single-family house project with a basement (solid construction). During the soil test, groundwater was found at a depth of 1.30 meters (4 feet 3 inches) – now our builder says the construction could cost €200,000 more due to the need for a waterproof concrete shell (“white tank”), pumping, sheet piling, etc. Can anyone share their experience with this? Is groundwater really such a costly issue? We have a meeting with our builder on Tuesday, but we would be interested in hearing your experiences beforehand.
Best regards
Nida35a schrieb:
@mmsbii1
please fill out the questionnaire,
right now we really don’t have enough information to helpWhich questionnaire do you mean?W
WilderSueden22 Jan 2023 22:35Nida35a schrieb:
With groundwater at 1.3m (4.3 feet), I wouldn’t build a basement; the water level can rise higher in wet years,That immediately makes me think of the house in water by Glatthaar.
mmsbii1 schrieb:
Which questionnaire do you mean?The questionnaire that is pinned at the beginning of the floor plan thread, I can’t link it,
@ypg can you please help me
M
motorradsilke23 Jan 2023 01:31Nida35a schrieb:
the questionnaire pinned at the beginning of the floor plan thread,
I can’t link it,
@ypg can you please help me? I’m not ypg, but I’m happy to help anyway 😉
https://www.hausbau-forum.de/threads/grundriss-planung-unbedingt-vor-beitrag-erstellung-lesen.11714/
Hello,
here is my opinion on the additional effort involved
Groundwater management during the construction period:
- Depending on how deep the excavation needs to go (at least 0.5 m (20 inches) below the base of the excavation)
- Only possible with vacuum pumps (must be planned by an engineering office), which need to be operated weeks in advance. The water is discharged into the sewer system. (Of course, this must be approved by the local authority/planning permission)
- Depending on the construction location, documentation of neighboring buildings might be necessary to protect against settlement damage caused by lowering the groundwater level.
- Since, in my assessment, the soil is sandy, the slopes must be designed at less than 45°. Depending on the excavation depth, the construction pits can quickly become quite large. An alternative is the use of shoring. In waterlogged sandy soil, sheet piling is best, as no water can then flow in from the sides. Soldier pile and lagging shoring is probably also possible.
Additionally, there is the basement waterproofing as a “grey tank” at the end.
It all depends on how deep you want to build the basement... However, a basement is not going to be cheap in any case.
here is my opinion on the additional effort involved
Groundwater management during the construction period:
- Depending on how deep the excavation needs to go (at least 0.5 m (20 inches) below the base of the excavation)
- Only possible with vacuum pumps (must be planned by an engineering office), which need to be operated weeks in advance. The water is discharged into the sewer system. (Of course, this must be approved by the local authority/planning permission)
- Depending on the construction location, documentation of neighboring buildings might be necessary to protect against settlement damage caused by lowering the groundwater level.
- Since, in my assessment, the soil is sandy, the slopes must be designed at less than 45°. Depending on the excavation depth, the construction pits can quickly become quite large. An alternative is the use of shoring. In waterlogged sandy soil, sheet piling is best, as no water can then flow in from the sides. Soldier pile and lagging shoring is probably also possible.
Additionally, there is the basement waterproofing as a “grey tank” at the end.
It all depends on how deep you want to build the basement... However, a basement is not going to be cheap in any case.
A
Allthewayup31 Jan 2023 21:56@mmsbii1
Water at 1.3m (4.3 ft) below ground level is already quite unfavorable. Depending on the soil conditions and the required setbacks from neighboring buildings, this can quickly become economically unfeasible.
For our construction project, I managed the dewatering myself, including all necessary calculations and applications. It definitely wasn’t easy, I can tell you that. However, we only had water at 2.5m (8.2 ft) below ground level, and fortunately, the soil was very gravelly.
Do you have a soil report? What exactly does it say about groundwater control during construction? I’m afraid you might need sheet piling. In a project nearby on my street, the neighboring house suffered serious damage due to the sheet piling. The sheets were too short, had to be removed and reinstalled, causing even more problems and costs. In that case, 200K wasn’t enough to cover the work and the damages to the neighbor’s building (4 residential units).
Personally, with that water level, I would have definitely given up on building a basement. Trust me, you won’t be happy. You can’t imagine how much water can accumulate in a short time. We lowered the water about 1m (3.3 ft) and had two pumps running almost nonstop. You can check my posts on this topic for more details.
Water at 1.3m (4.3 ft) below ground level is already quite unfavorable. Depending on the soil conditions and the required setbacks from neighboring buildings, this can quickly become economically unfeasible.
For our construction project, I managed the dewatering myself, including all necessary calculations and applications. It definitely wasn’t easy, I can tell you that. However, we only had water at 2.5m (8.2 ft) below ground level, and fortunately, the soil was very gravelly.
Do you have a soil report? What exactly does it say about groundwater control during construction? I’m afraid you might need sheet piling. In a project nearby on my street, the neighboring house suffered serious damage due to the sheet piling. The sheets were too short, had to be removed and reinstalled, causing even more problems and costs. In that case, 200K wasn’t enough to cover the work and the damages to the neighbor’s building (4 residential units).
Personally, with that water level, I would have definitely given up on building a basement. Trust me, you won’t be happy. You can’t imagine how much water can accumulate in a short time. We lowered the water about 1m (3.3 ft) and had two pumps running almost nonstop. You can check my posts on this topic for more details.
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