Hello to the forum,
My wife and I are planning to build a house. We have already chosen and reserved a plot of land. The plot has been filled and compacted with sand. Since it is a new development area, the construction company responsible for infrastructure provided a soil report for the site.
I have two questions regarding this:
1. The report states the following: The allowable bearing pressure was calculated for a strip footing with b = 0.50 m (20 inches) and t = 0.80 m (31 inches) as σ_allow = 160 kN/m².
2. Groundwater: During the geotechnical investigations, groundwater was encountered at about 1.00 m (40 inches) below the former ground surface level of the plot. This corresponds to a depth of approximately 7.80 m (26 feet) above sea level. Due to the implemented site elevation, groundwater is expected to be encountered at around 1.90 m (75 inches) below the current ground surface. Fluctuations in the water level cannot be ruled out.
Regarding point 1) I have read in the general building specifications from developers that the soil bearing capacity is usually considered to be 200 kN/m². Does this mean that the value mentioned above is insufficient and that additional measures will be necessary?
Regarding point 2) I am not sure, but do the measured values suggest that we have to expect a “wet” soil/subsoil? We are not planning a basement, but still—is this something to be concerned about?
How would you interpret both points from the report? My wife and I would be very grateful for any feedback and advice.
My wife and I are planning to build a house. We have already chosen and reserved a plot of land. The plot has been filled and compacted with sand. Since it is a new development area, the construction company responsible for infrastructure provided a soil report for the site.
I have two questions regarding this:
1. The report states the following: The allowable bearing pressure was calculated for a strip footing with b = 0.50 m (20 inches) and t = 0.80 m (31 inches) as σ_allow = 160 kN/m².
2. Groundwater: During the geotechnical investigations, groundwater was encountered at about 1.00 m (40 inches) below the former ground surface level of the plot. This corresponds to a depth of approximately 7.80 m (26 feet) above sea level. Due to the implemented site elevation, groundwater is expected to be encountered at around 1.90 m (75 inches) below the current ground surface. Fluctuations in the water level cannot be ruled out.
Regarding point 1) I have read in the general building specifications from developers that the soil bearing capacity is usually considered to be 200 kN/m². Does this mean that the value mentioned above is insufficient and that additional measures will be necessary?
Regarding point 2) I am not sure, but do the measured values suggest that we have to expect a “wet” soil/subsoil? We are not planning a basement, but still—is this something to be concerned about?
How would you interpret both points from the report? My wife and I would be very grateful for any feedback and advice.
I read in the general construction descriptions from the developers that a soil bearing capacity of 200kN/m² (approximately 4,200 psf) is specified. Does this mean the above value is not sufficient and additional measures need to be taken?Correct! Either the strip foundation is structurally designed differently, or a soil replacement must be carried out. In both cases, additional costs can be expected.
Regarding point 2) I am not sure, but could the determined values indicate that a "moist" soil/subgrade should be expected? We are not planning a basement, but still?The term "moist soil" refers to normal soil moisture. If you are planning a slab foundation only, that is building without a basement, this usually does not cause major issues. Any necessary waterproofing measures should be planned for normal soil moisture.
Hopegro
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