ᐅ Basement originally partially constructed with concrete, now possibly fully built with masonry.
Created on: 19 Jan 2017 00:04
K
Kaspatoo
Hi,
In previous discussions and offers, we agreed with our provider (architect/owner of the construction company, including their own site, excavator, employees, etc.) to build the basement roughly half in 24cm (10 inches) thick concrete and the other half with masonry.
The background is that we have a sloped site, and the basement is about half above ground level, containing two living rooms. The rooms at the rear, towards the slope, are a heating room, storage room, and bathroom.
We do not have a soil report. The soil is clay/loam-like (my father-in-law called it red marl). So, it is not very permeable. Above us runs the road, and beyond that, the slope continues for about 50-100m (55-110 yards), then you reach the top of the hill. Two more plots will be developed above us. The house and road are roughly at the same level (plus a step).
We now want to finalize the contract details. The architect recently called me and said he would prefer to build the entire basement with masonry (thickness unknown but thicker than 24cm (10 inches)), including drainage. The drainage would not clog because it would be in a gravel bed.
I have researched and, as expected, I am uncertain about which option is better and what questions I should ask the architect or what details should be agreed upon.
Basically, there are two methods: waterproof concrete (often called a white tank) and sealing with bitumen or plastic membranes (often called a black tank).
Regarding the cost of both options, I have read very different statements; for some, one was more expensive, for others, the other was. Or it was previously like that, but now they say the costs are about the same. The waterproof concrete method is said to be much more common nowadays.
I also found, but only from one source (other sites had exactly the same text), that bitumen variants last only about 30 years, while waterproof concrete easily lasts 80 years. Is there any truth to this? Has anyone had to remove their soil because water appeared after 30 years?
Back to the upcoming discussion with the architect. Should he provide a written guarantee of watertightness? Is the concrete method definitely waterproof and generally requires less long-term warranty? What else should I pay attention to (I won’t sign immediately, but a more confident approach wouldn’t hurt)? What might be a rough but reasonable wording for both options in the contract?
Thank you very much.
In previous discussions and offers, we agreed with our provider (architect/owner of the construction company, including their own site, excavator, employees, etc.) to build the basement roughly half in 24cm (10 inches) thick concrete and the other half with masonry.
The background is that we have a sloped site, and the basement is about half above ground level, containing two living rooms. The rooms at the rear, towards the slope, are a heating room, storage room, and bathroom.
We do not have a soil report. The soil is clay/loam-like (my father-in-law called it red marl). So, it is not very permeable. Above us runs the road, and beyond that, the slope continues for about 50-100m (55-110 yards), then you reach the top of the hill. Two more plots will be developed above us. The house and road are roughly at the same level (plus a step).
We now want to finalize the contract details. The architect recently called me and said he would prefer to build the entire basement with masonry (thickness unknown but thicker than 24cm (10 inches)), including drainage. The drainage would not clog because it would be in a gravel bed.
I have researched and, as expected, I am uncertain about which option is better and what questions I should ask the architect or what details should be agreed upon.
Basically, there are two methods: waterproof concrete (often called a white tank) and sealing with bitumen or plastic membranes (often called a black tank).
Regarding the cost of both options, I have read very different statements; for some, one was more expensive, for others, the other was. Or it was previously like that, but now they say the costs are about the same. The waterproof concrete method is said to be much more common nowadays.
I also found, but only from one source (other sites had exactly the same text), that bitumen variants last only about 30 years, while waterproof concrete easily lasts 80 years. Is there any truth to this? Has anyone had to remove their soil because water appeared after 30 years?
Back to the upcoming discussion with the architect. Should he provide a written guarantee of watertightness? Is the concrete method definitely waterproof and generally requires less long-term warranty? What else should I pay attention to (I won’t sign immediately, but a more confident approach wouldn’t hurt)? What might be a rough but reasonable wording for both options in the contract?
Thank you very much.
Kaspatoo schrieb:
We don’t have a soil survey. Kaspatoo schrieb:
I’ve done some research and, as expected, I’m uncertain about what is better and what questions I should ask the architect, or which details should be agreed upon. Honestly, why skip a soil survey to know the actual ground conditions?
And it’s bad enough that the architect apparently guesses what kind of basement is needed without proper information.
Drainage always makes sense whenever there is even the slightest suspicion of seepage problems. In the company, two people skipped it, and now, after 5 years, the building is moldy.
A proper exterior drainage system during the construction phase is not that expensive (doing it later will be costly...), and the excavation work with a powerful excavator is done quickly (for example, when digging the foundation for the house).
A soil survey is always a useful targeted consultation. Everyone recommends it, but the information is only accurate at one or a few locations at a specific time. In the end, you end up with a piece of paper costing around 1000 Euros that states what you already knew, and you could have invested that 1000 Euros directly into solving the problem.
A proper exterior drainage system during the construction phase is not that expensive (doing it later will be costly...), and the excavation work with a powerful excavator is done quickly (for example, when digging the foundation for the house).
A soil survey is always a useful targeted consultation. Everyone recommends it, but the information is only accurate at one or a few locations at a specific time. In the end, you end up with a piece of paper costing around 1000 Euros that states what you already knew, and you could have invested that 1000 Euros directly into solving the problem.
C
Caspar202019 Jan 2017 14:13A soil survey is necessary not only because of water-related issues but also to assess the soil’s load-bearing capacity and to determine whether soil replacement is required, if the slab/foundations need to be stronger or reinforced, and so on.
Hmm, depending on the composition (silt, clay, sand percentages) and consistency, it may only be marginally load-bearing.
Is the architect just pouring concrete into the hole without proper assessment, or what?
And have you factored in potential additional costs for increased disposal?
Kaspatoo schrieb:
The soil is clay/loam-like
Hmm, depending on the composition (silt, clay, sand percentages) and consistency, it may only be marginally load-bearing.
Is the architect just pouring concrete into the hole without proper assessment, or what?
And have you factored in potential additional costs for increased disposal?
No, we are even bringing in soil; I want to level it out because a sloped lawn is bad for playing ball.
The soil is known from neighboring properties.
But that’s not really what this is about.
I want to prepare for the conversation about the basement and show up not just with partial knowledge, but at least with semi-informed understanding.
The soil is known from neighboring properties.
But that’s not really what this is about.
I want to prepare for the conversation about the basement and show up not just with partial knowledge, but at least with semi-informed understanding.
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