Hello everyone,
our soil report arrived last week, and the earth appears to be of good quality and can be used for backfilling.
Unfortunately, a water exposure class W2.2-E was identified, and the developer therefore recommends a waterproof concrete basement structure ("white tank") due to the presence of groundwater pressure. The construction site is a vineyard with a gentle slope, and the winemaker who has worked the land for over 30 years told me in a conversation that he finds this surprising and does not understand where the groundwater pressure would come from.
Of course, we are both laypeople, so my question is: I have heard that soil experts nowadays tend to be cautious and assume a worst-case scenario. Would you install a waterproof concrete basement in this exposure class? What information would you need to be able to give advice on this?
Thank you!
our soil report arrived last week, and the earth appears to be of good quality and can be used for backfilling.
Unfortunately, a water exposure class W2.2-E was identified, and the developer therefore recommends a waterproof concrete basement structure ("white tank") due to the presence of groundwater pressure. The construction site is a vineyard with a gentle slope, and the winemaker who has worked the land for over 30 years told me in a conversation that he finds this surprising and does not understand where the groundwater pressure would come from.
Of course, we are both laypeople, so my question is: I have heard that soil experts nowadays tend to be cautious and assume a worst-case scenario. Would you install a waterproof concrete basement in this exposure class? What information would you need to be able to give advice on this?
Thank you!
A
Allthewayup2 Apr 2023 23:19Something else occurred to me:
It might be worth calling the geologist again to ask if they see an alternative to the waterproof concrete basement shell (white tank). I am not familiar with the local conditions, but perhaps there is a possibility to refill the excavation after the basement is built using highly permeable soil and to eliminate the risk of occasionally accumulating groundwater layers with a sufficiently sized drainage system. The question is whether this makes financial sense in the end.
It might be worth calling the geologist again to ask if they see an alternative to the waterproof concrete basement shell (white tank). I am not familiar with the local conditions, but perhaps there is a possibility to refill the excavation after the basement is built using highly permeable soil and to eliminate the risk of occasionally accumulating groundwater layers with a sufficiently sized drainage system. The question is whether this makes financial sense in the end.
Thank you. That already helps me a lot. According to the developer, the basement will be constructed from precast concrete elements made of waterproof concrete. The "white tank" is basically an additional waterproofing layer applied on top, right? We’ll probably just do that to be on the safe side. We also have three basement windows that are about 150 cm (60 inches) below ground level, all on the downhill side of the house. Because of the exposure class 2.2, the developer wanted to install special concrete light wells for these, which would each cost an additional 10,000 euros. Is that really necessary?
There is no such thing as a "white tank" waterproofing on its own — it is simply a principle or system made up of several components. This includes waterproof concrete (WU concrete), crack width limitations achieved through additional steel reinforcement, specific dimensioning requirements regarding wall thicknesses, certain restrictions related to built-in elements, and sealing systems for construction and expansion joints (e.g., Pentaflex, etc.), as well as for all penetrations (multiple pipes, drain pipes, etc.). In practice, only the steel reinforcement and joint tapes or joint sheets are really relevant as cost drivers.
The ACO plastic light wells can all be installed to be watertight against pressurized water — so I don’t see why you would need concrete wells...
The ACO plastic light wells can all be installed to be watertight against pressurized water — so I don’t see why you would need concrete wells...
H
hanghaus20233 Apr 2023 11:56Swoti schrieb:
We still have three basement windows located about 150 cm (5 feet) below the finished ground level, all on the downhill side of the house. The developer wanted to install special concrete window wells due to soil class 2.2, which would each cost an additional 10,000 euros. Is that really necessary? Who installs basement windows 1.5 m (5 feet) deep?
In my opinion, the suggestion about drainage is a good idea. Then you wouldn't need special concrete window wells.
Show us the site plan of the house with elevation levels.
X
xMisterDx3 Apr 2023 17:06What incentive does the assessor have to compromise and say, "Yes, that could work..."?
They adjust the report accordingly, and then three years later, the builder takes them to court because after the first heavy rain, it didn’t work and the basement flooded.
Ultimately, the decision is up to the builder, who has to find a construction company that doesn’t mind that.
Such companies do exist. Neighbors a few houses down were advised by the geologist to use driven piles for foundation reinforcement... but they built on a sand cushion with a different general contractor, without strip foundations... and it worked. The question is whether they will be happy with that in the end.
And what the winemaker says... well, he knows about wine. I don’t ask a mason which wine over $25 per bottle he recommends.
They adjust the report accordingly, and then three years later, the builder takes them to court because after the first heavy rain, it didn’t work and the basement flooded.
Ultimately, the decision is up to the builder, who has to find a construction company that doesn’t mind that.
Such companies do exist. Neighbors a few houses down were advised by the geologist to use driven piles for foundation reinforcement... but they built on a sand cushion with a different general contractor, without strip foundations... and it worked. The question is whether they will be happy with that in the end.
And what the winemaker says... well, he knows about wine. I don’t ask a mason which wine over $25 per bottle he recommends.
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