ᐅ Groundwater-related costs: experiences and implications?

Created on: 22 Jan 2023 12:14
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mmsbii1
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mmsbii1
22 Jan 2023 12:14
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
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hanghaus2023
22 Jan 2023 13:13
The waterproof concrete shell is probably the necessary solution. Whether extreme costs such as sheet piling, water management, etc., are required cannot be assessed here. That is what the geotechnical engineer states in their recommendation. Please share it here.

Without a basement is then the lesser evil.
Nida35a22 Jan 2023 14:32
Welcome to the forum,
with a groundwater level of 1.3m (4.3 feet), I would not build a basement. The water level can rise higher in wet years,
then it will flow into the basement light wells, and basement windows are not submarine windows.
If the site is lower, it will flood faster.
Does the floor area ratio allow for a larger footprint, or are you already at the limit?
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mmsbii1
22 Jan 2023 14:53
Nida35a schrieb:

Welcome to the forum,
with a groundwater level of 1.3m (4.3 ft), I wouldn’t recommend building a basement. The water table can rise higher in wet years,
which can cause water to enter the basement light wells, and basement windows are not designed to be watertight.
If your plot is lower, it will flood more quickly.
Does the floor area ratio allow for a larger footprint, or are you already at the limit?

Unfortunately, we are already at the limit, and the allowed area is really small, 100m2 (1,076 sq ft).
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Reggert
22 Jan 2023 14:53
Water at a depth of 1.3m (4 feet 3 inches)... you should probably consider building on stilts if there’s a particularly rainy year 😀
I would skip the basement in that case since it would basically always be underwater, right?
Nida35a22 Jan 2023 15:04
@mmsbii1
please fill out the questionnaire,
right now we really don’t have enough information to be able to help you