Correctly interpreting the results of a geotechnical report

  • Erstellt am 2020-02-28 13:00:55

Kohorte

2020-02-28 13:00:55
  • #1
Hello again,
As the planning progresses, the questions increase.
We are building on a slope. One house wall will be placed into the ground. (Sections: )
The soil report showed: well load-bearing soil of class 4, (5 if you find larger stones on it (isn't that always the case?))
Topsoil 20cm. No pressing water. With heavy rainfall, water just passes through the slope.
Frost level F3 (F2 is required).
Three foundation options are recommended:
1.1 Dst foundation 65cm deep with 50cm overhang. Then we need a cushion drainage.
1.2 Dst foundation >80cm and 65cm overhang. Then cushion drainage is not necessary.
2. Strip foundation should be at least 0.5m deep on the valley side in layer 3. That starts at 60cm. (Here the frost-proof foundation depth >1m is stated)

Drainage is necessary on all variants on the earth-contacting wall.

Dst foundation is apparently cheaper. Even with cushion drainage? Or with 80cm?
What is better? Making the cushion thicker or the drainage?
And how much more expensive are strip foundations? Should we generally rather go for strip foundations then? So are the advantages that clear? Of course, we don’t want to save in the wrong place. But if all foundation options are OK, we would certainly also consider the price.

Regarding earthworks: here, in a very short summary, it says something about the backward method, that cushion material should be applied immediately in layers, by pre-head dumping.

Is that unusual?

I actually have the greatest respect for this part of the house construction and want to be prepared for the conversation and, most importantly, of course, be able to assess whether the estimated costs can be correct or how much buffer we need to plan and choose the "right" variant.

Thanks already!!
 

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