Basement originally partially concrete, now possibly completely brick-built

  • Erstellt am 2017-01-19 00:04:26

Kaspatoo

2017-01-19 00:04:26
  • #1
Hi,

in previous discussions and offers, we have agreed with our provider (architect/owner of the construction company (=own yard, excavator, employees, etc.)) to construct the basement roughly half in 24cm thick concrete and the other half to be built with masonry.

The background is that we have a hillside location and the basement is about half above ground and contains two living rooms. The rear rooms facing the hill are a heating cellar, storage room, and bathroom.

We do not have a soil survey. The soil is clayey/loamy (father-in-law called it red marl). So not particularly permeable. Above us runs the road, above that the hillside continues about 50-100m further, then you are already "at the summit." Above us, two more plots of land are being developed. House and road are approximately at the same level (plus a step).

We now want to make a precise contract design. The architect has now called me and said he would prefer to do it differently and build the basement completely with masonry (thickness I no longer know, but thicker than 24cm), including drainage. The latter would not clog up either, as it is in a gravel bed.

I have informed myself and, as expected, am uncertain about what is better now, and what questions I should possibly ask the architect, or which details should be agreed upon.

Basically, there are two methods with WU concrete (often referred to as [Weiße Wanne]) and sealed with bitumen or plastic layers (often referred to as [Schwarze Wanne]).

Regarding the costs of both variants, I have read very different statements; for some, one was more expensive, for others the other. Or it used to be that way in the past, but now it is equally expensive. The WU concrete variant is nowadays significantly more common.

What I also found, but only in one source (other pages had exactly the same text), is that bitumen variants only last 30 years and WU easily 80 years. Is there any truth to that? Has anyone ever had to remove their soil because water came after 30 years?

Back to the architect conversation that is upcoming. Should he guarantee tightness in writing? Is a concrete variant definitely watertight and requires rather less of a lengthy guarantee? What else should I pay attention to (I won't sign immediately, but a somewhat more confident appearance does no harm). What would be a rough formulation for both variants, how should it be reasonably worded?

Thank you very much.
 

RobsonMKK

2017-01-19 12:16:26
  • #2



Honestly, why no soil report to know what’s going on?
And bad enough that the architect apparently is guessing what kind of basement should be built.
 

Kaspatoo

2017-01-19 12:29:52
  • #3
The architect is already building another house directly below us.
 

Payday

2017-01-19 13:06:13
  • #4
Drainage always makes sense at the moment when there is even the slightest suspicion of seepage problems. In the company, two people saved on it and now the place has been moldy after 5 years. A proper external drainage during the construction phase is not that expensive (it will be expensive afterwards...), the digging work with a powerful excavator is quickly done (e.g. when digging the foundation for the house...). A soil survey is always a great targeted guessing session. Everyone recommends it, but the information content is only correct at 1-x points at a time x. In the end, you have a piece of paper for 1000€ that says what you already knew and could have invested the 1000€ directly into solving the problem.
 

Caspar2020

2017-01-19 14:13:20
  • #5
A soil survey is needed not only because of the issue with water, but also to check the bearing capacity of the ground, and to determine whether soil replacement is necessary, whether the slab/foundations need to be stronger and/or stiffened, etc.



Hmm, depending on the composition (silt, clay, sand content) and consistency, it may also be only limitedly load-bearing.

Is the architect just pouring the concrete into the hole on a whim, or what?

And have you taken any potential additional costs for increased disposal into account?
 

Kaspatoo

2017-01-19 17:24:25
  • #6
no, we are even bringing in soil, I want to level it, a slanted lawn is bad for playing ball
the ground is known from neighboring properties

but that's not what I'm concerned about here
I want to prepare for the conversation about the basement and not show up there with only partial knowledge, but at least with half-knowledge.
 

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