ᐅ Rising groundwater / basement: yes or no?

Created on: 29 Aug 2014 16:59
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fex84
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fex84
29 Aug 2014 16:59
My girlfriend and I are facing the big question... basement yes or no?

We have already had a geotechnical survey done for the plot and are now wondering if it makes sense to build a basement there.

I would really like to have a basement (not a living basement). Mainly because of my six bicycles, which were not exactly cheap, and the desire for a workshop. My girlfriend is a bit hesitant about building a basement due to the high groundwater pressure. She is worried that the waterproof concrete shell (“white tank”) might not hold and that constructing such a basement on our plot could become very expensive.

On the other hand, building a slab foundation on the plot is also not easy, as the soil would first need to be excavated.

I have already read through numerous forums and am aware of the risks of a waterproof basement with high groundwater pressure. However, I don’t think I can really save money by building without a basement, since instead of a wooden carport, I would prefer a large garage with an extension.

What do you think? Is building a basement on our plot really risky and expensive? Is it cheaper to skip the basement and build a large garage with an extension instead?
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fex84
29 Aug 2014 17:21
Oh, I see. The plan is for a single-family house with about 150-160 m² (1600-1700 sq ft) / the plot is 550 m² (6000 sq ft) in size.
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Manu1976
30 Aug 2014 19:01
No one can really answer that question for you. You’re probably already aware of the advantages and disadvantages.
We also have high groundwater pressure and decided against a waterproof concrete basement (a “white tank”) and therefore no basement at all. Instead, we are building a bit taller and have plenty of storage space under the roof. However, we don’t have six bicycles (although, if I count them all together, we actually do).
If I were you, I would plan the garage a bit larger and include a workshop there as well, so you don’t have to carry the bikes up and down. Your lot should be big enough for that.
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Bauexperte
1 Sep 2014 14:02
Hello,
fex84 schrieb:

My girlfriend and I are facing the big question... basement yes or no? The plan is a single-family house with about 150-160 sqm (1600-1700 sq ft) / the plot is 550 sqm (5900 sq ft) in size.
fex84 schrieb:

On the other hand, constructing a slab foundation on the plot is not exactly easy either, as the soil would first have to be removed.
You don’t just have to add soil, there is also actually a shortage of earth.
fex84 schrieb:

I have already read through all the forums and am aware of the risks of a waterproof (WU) basement with groundwater pressure.
However, I don’t think I can really save money by building without a basement, since instead of a wooden carport, I would prefer a large garage with an extension.
A waterproof basement built according to DIN 18xyz standards and based on the soil report carries no risks at all. If you both feel uncertain, you should hire an independent expert to accompany you during construction supervision.
fex84 schrieb:

What do you think? Is building a basement on our plot really risky and expensive?
More expensive than on “normal” plots, yes. Risky – with technically flawless construction: no.
fex84 schrieb:

Is it cheaper to forgo a basement and instead build a large garage with an extension?
Under normal conditions: always. However, due to the additional foundation costs on your plot, the basement will become even more costly. I estimate around 42,000 EUR for the usable basement and another 8,000 to 9,000 EUR for the required waterproof sealing.

I haven’t calculated how many centimeters (inches) of soil would need to be replaced and added for the slab foundation. But even if this also costs 8,000 to 9,000 EUR, the prefabricated garage costs about 10,000 EUR all-in. So, in reality, there is a saving of around 23,000 EUR compared to a usable basement.
fex84 schrieb:

In the following link you will find excerpts from our soil report
It would be nice if the next download offer could be provided without unwanted background noise.

Best regards, Bauexperte