Dear community,
I am reaching out because I am currently uncertain and, even after consulting specialists, I still do not have a clear answer.
We are building a house (KFW 40 standard, made of Poroton) on a slope, and our basement is partially underground. The plan was for the basement to be a "white tank" waterproofing system. However, we were recently informed that the basement will be built using Poroton T7 blocks (42.5cm (17 inches) thick), essentially a "black tank" system. Additionally, drainage will be installed.
Switching to a white tank would delay the start of construction.
My question is, would you insist on the white tank method? Generally, the black tank is considered to have a shorter lifespan, but for living comfort, the Poroton basement is supposed to be more pleasant.
I would also be interested to know if the basement made from Poroton T7 blocks might even be less expensive for the builder.
I hope you can help me.
I am reaching out because I am currently uncertain and, even after consulting specialists, I still do not have a clear answer.
We are building a house (KFW 40 standard, made of Poroton) on a slope, and our basement is partially underground. The plan was for the basement to be a "white tank" waterproofing system. However, we were recently informed that the basement will be built using Poroton T7 blocks (42.5cm (17 inches) thick), essentially a "black tank" system. Additionally, drainage will be installed.
Switching to a white tank would delay the start of construction.
My question is, would you insist on the white tank method? Generally, the black tank is considered to have a shorter lifespan, but for living comfort, the Poroton basement is supposed to be more pleasant.
I would also be interested to know if the basement made from Poroton T7 blocks might even be less expensive for the builder.
I hope you can help me.
R
Robert199528 Jan 2024 10:23Hello and first of all, thank you for the replies.
I’m currently a bit at a loss.
According to the soil survey, it appears to be rising seepage water.
The shell construction company was selected by the developer after a tender, and it is assumed that the cheapest one was chosen.
This company either cannot provide a waterproof concrete shell (often called a “white tank”) or claims it would not be feasible within the time frame. However, I strongly suspect that the order was placed too late.
So far, no credit has been offered regarding the “lower-quality basement.” Rather, the statement was that the costs for the Poroton basement would be higher and better.
According to the developer, the energy efficiency value could have been achieved with both options.
According to the contract, a waterproof concrete shell (white tank) was agreed upon, but according to the developer, only for the walls in contact with the soil.
This raises the question: Is it even advisable to build half of the basement with waterproof concrete and the rest with Poroton blocks? Considering the expansion and movement of the materials?
I am attaching the plans I have. I hope you can make some sense of them.
I’m currently a bit at a loss.
According to the soil survey, it appears to be rising seepage water.
The shell construction company was selected by the developer after a tender, and it is assumed that the cheapest one was chosen.
This company either cannot provide a waterproof concrete shell (often called a “white tank”) or claims it would not be feasible within the time frame. However, I strongly suspect that the order was placed too late.
So far, no credit has been offered regarding the “lower-quality basement.” Rather, the statement was that the costs for the Poroton basement would be higher and better.
According to the developer, the energy efficiency value could have been achieved with both options.
According to the contract, a waterproof concrete shell (white tank) was agreed upon, but according to the developer, only for the walls in contact with the soil.
This raises the question: Is it even advisable to build half of the basement with waterproof concrete and the rest with Poroton blocks? Considering the expansion and movement of the materials?
I am attaching the plans I have. I hope you can make some sense of them.
J
jens.knoedel28 Jan 2024 10:32Robert1995 schrieb:
According to the contract, a waterproof concrete shell ("white tank") was agreed upon,Then the matter is settled. Robert1995 schrieb:
According to the soil report, it appears to be rising seepage water.Insist in writing on the fulfillment of the waterproof concrete shell.G
Gerddieter28 Jan 2024 10:36Yes, that's great – then just go with half of the white tub!
Tell us who is actually building now – general contractor, main contractor, developer, or are you managing the contract yourself?
As @11ant already mentioned, a lot depends on that when it comes to what claims you have and against whom...
Tell us who is actually building now – general contractor, main contractor, developer, or are you managing the contract yourself?
As @11ant already mentioned, a lot depends on that when it comes to what claims you have and against whom...
R
Robert199528 Jan 2024 12:00Hi, I completely overlooked this; it is a general contractor.
H
hanghaus202328 Jan 2024 12:13Robert1995 schrieb:
According to the soil report, it is likely rising seepage water. You can assume that on a slope. In that case, using a waterproof concrete basement is the safer choice.
Robert1995 schrieb:
The shell construction company was selected by the developer after a tender process, and it is assumed that the cheapest option was chosen.
This company either cannot provide a waterproof concrete basement or believes it is not feasible within the timeframe. I also strongly suspect it was ordered too late. You can assume that the waterproof concrete basement is more expensive and was not included in the builder’s low-cost offer. The developer usually keeps the difference as profit.
Robert1995 schrieb:
So far, no credit has been offered to us regarding the “lower quality basement,” rather the statement was that the costs for the Poroton basement were higher and better. As a contractor, I would make the same claim. In this case, demand a verifiable cost reduction claim.
Robert1995 schrieb:
According to the developer, the energy efficiency target could have been achieved with both options. Technically, that is easily achievable.
Robert1995 schrieb:
The contract stipulated a waterproof concrete basement, but according to the developer, only for the walls that are below ground level.
Now I have a question: Is it actually reasonable to build a half-basement with waterproof concrete and the rest from Poroton blocks? Considering material expansion and movement? If that is contractually agreed, then technically there is no problem. This is common practice. However, whether the contractor takes this risk regarding warranty claims is questionable.
Robert1995 schrieb:
Attached are the plans I have. I hope you can make some use of them. Thank you, that helps.
H
hanghaus202328 Jan 2024 12:24The plan for the basement does not show a half bathroom.
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