C
claudiamm7 Sep 2010 16:05I have a few questions about basements. We plan to build next year. An expert report showed that we have to expect hydrostatic pressure on our plot in Schleswig-Holstein. In addition, the groundwater is highly aggressive to concrete. However, we do not want to give up having a basement. Online, you often read horror stories from people who built basements that ended up damp and cold, with mold and decay. Of course, we want to avoid that. We also plan to use our basement as living space. What do you think is the best solution? We are quite uncertain because you often hear negative things about solutions like the “white tank” (watertight concrete basement). Does anyone have advice?
Waterproof Basement
This will be quite expensive.
Aside from that, your warranty period is a maximum of 5 years. And then? But maybe there is someone who offers more. In that case, they should also still be available in the event of damage.
This will be quite expensive.
Aside from that, your warranty period is a maximum of 5 years. And then? But maybe there is someone who offers more. In that case, they should also still be available in the event of damage.
claudiamm schrieb:
I have a few questions about basements. We plan to build next year. An expert report showed that we need to expect hydrostatic pressure on our property in Schleswig-Holstein. In addition, the groundwater is highly aggressive to concrete. However, we do not want to do without a basement. You often read horror stories online from people who built basements that turned out damp and cold, with mold and decay. Of course, we want to avoid that. We plan to use our basement as living space. What do you think is the best solution? We are quite uncertain, because there are always negative reports about solutions like the “white tank” (waterproof concrete tank).
Does anyone have advice?
C
claudiamm10 Sep 2010 11:07Waterproof Concrete Basement
Hello Baufixx,
How expensive do you think this could be? Do you have any experience with it? And aside from the price, what would be the best solution?
Hello Baufixx,
How expensive do you think this could be? Do you have any experience with it? And aside from the price, what would be the best solution?
Baufixx schrieb:
That will get really expensive.
B
Bauexperte10 Sep 2010 18:07Hello,
Just as a side note: I haven’t heard or read such nonsense in a long time. Water will always find its way—regardless of any obstacles in its path. The “colleague” home seller seems very “creative” if this statement is based on their information.
Aside from the fact that such a basement will certainly add an extra cost of around ten thousand euros (TEUR +/- 10) (depending on the size of the house)...
A “white tank” is the result of soil conditions; when properly executed—possibly not by a self-builder—there is nothing wrong with it.
Kind regards
claudiamm schrieb:
...Also, the water is highly aggressive to the concrete...
Just as a side note: I haven’t heard or read such nonsense in a long time. Water will always find its way—regardless of any obstacles in its path. The “colleague” home seller seems very “creative” if this statement is based on their information.
claudiamm schrieb:
...We want to use our basement as living space. In your opinion, what is the best solution?
Aside from the fact that such a basement will certainly add an extra cost of around ten thousand euros (TEUR +/- 10) (depending on the size of the house)...
claudiamm schrieb:
...We are quite uncertain because you often hear negative things about solutions like the "white tank" (waterproof concrete shell). Does anyone have advice?
A “white tank” is the result of soil conditions; when properly executed—possibly not by a self-builder—there is nothing wrong with it.
Kind regards
B
Bauexperte14 Sep 2010 11:14Hello,
This is by no means polemic, more like gallows humor.
This standard defines criteria for assessing the aggressiveness of primarily natural waters composed of soils and gases containing substances that attack hardened concrete according to DIN 1045. It does not apply to concentrated solutions such as certain industrial wastewaters.
"Aggressive water" refers to water containing components that cause intensified chemical reactions. Free excess carbonic acid, for example, can lead to water that is aggressive to lime, which is important both in natural karst formation and technical contexts. The degree of water aggressiveness is a measure of the water’s ability to dissolve materials. Even distilled water can dissolve minerals from solids.
Building waterproofing: watertight / water-resistant
The necessary waterproofing measures depend on the water tightness of the existing soil or individual soil layers and the height of the groundwater level. This information can be obtained through appropriate soil investigations (geotechnical report). It is important to note that the groundwater level should be determined as the highest long-term level (over a period of several years). Some local authorities may also provide initial information about the groundwater level.
Regarding exposure, the following distinctions apply:
Soil moisture and non-stagnant percolating water with sufficiently permeable soil and the highest groundwater level below the foundation level; perched water with soils of lower permeability (clayey soils) and without drainage, if the highest groundwater level is at least 300mm (12 inches) below the foundation level (i.e., when soil type and terrain form suggest only stagnant water) and for foundation depths up to 3m (10 feet),
or
pressurized water for buildings with foundation levels below the highest groundwater level or within the groundwater-bearing stratum, regardless of foundation depth, immersion depth, or soil type.
Typically, one of the following two waterproofing methods is applied:
1. Water-resistant concrete (WU concrete or “white tank”):
Using a special concrete mix and reinforcement, along with meeting certain requirements, a water-resistant reinforced concrete shell is constructed. Water-resistant does not mean “watertight.” While a watertight material neither allows water ingress nor penetration, a water-resistant material reduces water transport through it so much that any water passing through can evaporate on the air-facing side. This is important to consider if higher-value use of basement rooms is planned (living areas, if permitted by building regulations; hobby rooms, etc.), as water-resistant components without additional compensation may lead to increased indoor humidity. Furthermore, vapor-tight coverings (e.g., PVC or tiles) must not be applied directly to WU concrete structures.
2. Waterproof materials (“black tank”):
For this method, basement components are sealed with coatings or membrane systems, depending on the exposure described above.
Both methods have advantages and disadvantages, for example regarding costs, the ability to repair defects, implications for basement finishing and usage, construction sequence, etc. The decision whether or not to have a basement and which waterproofing method to choose should therefore be made in close consultation with the architect or a specialist planner. Attention should also be given to this aspect when purchasing a property.
Although the cost of waterproofing measures is only a small part of the total construction cost, waterproofing is economically very important. If not fully functional, it can lead to costly damage and repairs since access to these waterproofing measures is very limited or impossible after construction completion.
Your report indicates how your preferred builder should execute the basement; moreover, the geologist could probably alleviate your concerns about WU concrete if you were to ask him.
Best regards
claudiamm schrieb:
I find this kind of polemic not very helpful
This is by no means polemic, more like gallows humor.
claudiamm schrieb:
The fact is that we have a test report on the groundwater, an "Assessment of the degree of attack on concrete according to DIN 4030 Part 1". And the result clearly shows that the water is highly aggressive to concrete. Hence our concerns regarding waterproof concrete.
This standard defines criteria for assessing the aggressiveness of primarily natural waters composed of soils and gases containing substances that attack hardened concrete according to DIN 1045. It does not apply to concentrated solutions such as certain industrial wastewaters.
"Aggressive water" refers to water containing components that cause intensified chemical reactions. Free excess carbonic acid, for example, can lead to water that is aggressive to lime, which is important both in natural karst formation and technical contexts. The degree of water aggressiveness is a measure of the water’s ability to dissolve materials. Even distilled water can dissolve minerals from solids.
Building waterproofing: watertight / water-resistant
The necessary waterproofing measures depend on the water tightness of the existing soil or individual soil layers and the height of the groundwater level. This information can be obtained through appropriate soil investigations (geotechnical report). It is important to note that the groundwater level should be determined as the highest long-term level (over a period of several years). Some local authorities may also provide initial information about the groundwater level.
Regarding exposure, the following distinctions apply:
Soil moisture and non-stagnant percolating water with sufficiently permeable soil and the highest groundwater level below the foundation level; perched water with soils of lower permeability (clayey soils) and without drainage, if the highest groundwater level is at least 300mm (12 inches) below the foundation level (i.e., when soil type and terrain form suggest only stagnant water) and for foundation depths up to 3m (10 feet),
or
pressurized water for buildings with foundation levels below the highest groundwater level or within the groundwater-bearing stratum, regardless of foundation depth, immersion depth, or soil type.
Typically, one of the following two waterproofing methods is applied:
1. Water-resistant concrete (WU concrete or “white tank”):
Using a special concrete mix and reinforcement, along with meeting certain requirements, a water-resistant reinforced concrete shell is constructed. Water-resistant does not mean “watertight.” While a watertight material neither allows water ingress nor penetration, a water-resistant material reduces water transport through it so much that any water passing through can evaporate on the air-facing side. This is important to consider if higher-value use of basement rooms is planned (living areas, if permitted by building regulations; hobby rooms, etc.), as water-resistant components without additional compensation may lead to increased indoor humidity. Furthermore, vapor-tight coverings (e.g., PVC or tiles) must not be applied directly to WU concrete structures.
2. Waterproof materials (“black tank”):
For this method, basement components are sealed with coatings or membrane systems, depending on the exposure described above.
Both methods have advantages and disadvantages, for example regarding costs, the ability to repair defects, implications for basement finishing and usage, construction sequence, etc. The decision whether or not to have a basement and which waterproofing method to choose should therefore be made in close consultation with the architect or a specialist planner. Attention should also be given to this aspect when purchasing a property.
Although the cost of waterproofing measures is only a small part of the total construction cost, waterproofing is economically very important. If not fully functional, it can lead to costly damage and repairs since access to these waterproofing measures is very limited or impossible after construction completion.
Your report indicates how your preferred builder should execute the basement; moreover, the geologist could probably alleviate your concerns about WU concrete if you were to ask him.
Best regards
alternative
Hello Claudia,
there is now an alternative. I came across the ABG basement waterproofing system at a trade fair in the spring and discussed it with our architect. It was new to him as well. However, he thinks it could be a very useful solution for us, especially since we also have groundwater pressure. It originates from fuel station construction. Simply put, where no leaks occur at a fuel station, no water enters the house.
MartinW
Hello Claudia,
there is now an alternative. I came across the ABG basement waterproofing system at a trade fair in the spring and discussed it with our architect. It was new to him as well. However, he thinks it could be a very useful solution for us, especially since we also have groundwater pressure. It originates from fuel station construction. Simply put, where no leaks occur at a fuel station, no water enters the house.
MartinW
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