Basement planning without soil report

  • Erstellt am 2016-07-17 11:45:07

henning89

2016-07-17 11:45:07
  • #1
Hello,

I am planning to build a single-family house with a basement in Hamburg. Since I am purchasing the plot from the city, there are some special requirements, for example, I have to get the house design approved by a special advisory board (IBA Hamburg). Unfortunately, this is the only way to get a building plot at an affordable price.

As a result, I have to commit to a house design from a construction company before a soil survey is possible. Furthermore, I would like to build with a basement because, due to the requirements, more floor area on the ground floor and upper floor is not possible. The basement is intended for hobby purposes and as storage/utility room (by having the utility room in the basement, I gain the additional necessary room on the ground floor).

The following is known about the building ground so far:
"The building ground in Fischbeker Heidbrook is characterized by sands and mixed-grain soils such as till loam and silts. In areas with low hydraulic permeability of the soils, weather-related occurrences of perched water are to be expected. The groundwater level is between approximately 4 and 13 m depth."

Furthermore, discharge of drainage into a sewer is not permitted. Therefore, I have asked the construction company to initially plan the basement as a white tank.

My question now is whether the specifications in the offer correspond to a white tank, as the term is not explicitly mentioned.

"Reinforced concrete basement floor C 25/30 XC 4, clean layer made of a Delta MS dimple membrane, reinforcement 2x Q524, thickness 25cm"

"Basement exterior walls made of hollow wall elements with in-situ concrete C 25/30 XC 4, thickness 30cm, including joint sheet in the transition area wall/floor, wall reinforcement 2x Q257"

"Horizontal sealing on the basement floor under the interior walls with a Delta-Softflex, overlapping 10 cm inward"

"Basement exterior sealing:
Creation and shaping of a sealing fillet in the wall base area with a mineral mortar and a silicification process according to the manufacturer's specifications.
All edges milled, substrate cleaned of light contamination.
Application of a filling and scratch coat as pore closure on the primed surfaces, according to DIN 18195, edition 2000-08 with a 2-component plastic-modified bituminous thick coating. Sealing of the surfaces against rising seepage water, according to DIN 18195 part 6, point 9, edition 2000-08 with KMB and full-surface fabric reinforcement. Dry layer thickness 4mm. Layer thickness check and documentation according to DIN 198195 part 3, paragraph 5.4.4."

"Sealing of the plinth surfaces of the basement exterior masonry horizontally and vertically with a plastic-modified bituminous thick coating and fabric reinforcement in the base area"

The basement insulation (KFW40) is done with 160mm WLZ038 under the floor and 180mm WLZ031 on the walls.
 

tomtom79

2016-07-17 12:26:38
  • #2
A channel introduction of a drainage is also not allowed here but a soakaway pit is!

What is stopping you from paying for a soil survey yourself before the next steps are due!
 

MarcWen

2016-07-17 13:14:51
  • #3
I don’t understand it. With every car purchase, you do 1-2 inspections, test drives, then insure the car with comprehensive coverage, but when buying a house, people avoid necessary soil surveys or insurance.
 

henning89

2016-07-17 13:37:40
  • #4
I would like to have a soil survey done, but the development area is just being developed and the seller (City of Hamburg) does not yet allow me onto the property... The plots have not even been staked out yet, so the soil surveyor would first have to measure it himself. The situation is certainly not optimal, however I have no influence on the framework conditions and other reasonably affordable plots are not in sight. I have reserved the plot so far and am only allowed to buy it after I have an approved building permit. The whole thing is associated with certain deadlines, which means planning must begin before a soil survey. The survey will definitely be done before construction begins. However, I want to estimate the construction costs beforehand and have therefore asked the contractor to calculate a white tank as a precautionary measure. My question is therefore whether the offer corresponds to a white tank. Is, for example, concrete XC 4 = WU concrete?
 

Bauexperte

2016-07-17 15:12:09
  • #5

The planned execution is based on the soil conditions known so far.

Rhenish regards
 

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