ᐅ Estimating the amount of earthworks excavation

400 sqm (4300 sq ft) sounds realistic. But 6 meters (20 ft) house width (outer edge)? Even for a terraced house, that would be very, very tight.

Turbomicha schrieb:
Hello everyone,

I am about to build a semi-detached house with a basement. The house dimensions are 6 x 12.5 m (20 x 41 feet).
I would like to find out how much the earth excavation might cost. For that, I need to know how many cubic meters I will have to dispose of.
What do you think I should expect?

Best regards,
Michi

Disposal costs depend on how much material you plan to reuse.

Excavation volume depends on the soil type. Whether the slope angle is 60 degrees or 45 degrees makes a big difference.

Also, it’s unclear whether you might need soil replacement.

Turbomicha schrieb:
Hello everyone,

I’m about to build a semi-detached house with a basement. The house dimensions are 6 x 12.5 m (20 x 41 feet).
I’m interested in finding out how much the excavation will cost. For that, I would need to know how many cubic meters of soil I will need to dispose of.
What do you think I should expect?

Regards,
Michi

In the first step, you can estimate using 7 x 13.5 x 3.00 = 283.5 cubic meters x excavation cost per cubic meter; this will give you an approximate value. The amount will increase depending on the foundation recommendation from the geotechnical engineer. Then, of course, the type of soil and the disposal fees charged by the landfill must be considered.

Bauexperte

Bauexperte schrieb:
In the first step, you can calculate based on 7 x 13.5 x 3.00 = 283.5 cubic meters (cbm) multiplied by the excavation cost per cubic meter; this will give you an approximate value. The volume will increase depending on the foundation recommendations from the geologist. Then, of course, it depends on the type of soil and the disposal costs charged by the landfill for that soil.

Bauexperte

Bauexperte, for a vertical slope I calculate about 500 cubic meters (cbm) at a 45-degree angle.

You need at least 80cm (31.5 inches) of working space plus a slope, so you should generally allow at least 1m (39 inches) in every direction. This results in approximately 8 x 14.5 x 3 cubic meters (cubic yards) of gravel and concrete slab material. Additionally, you need to apply a loosening factor because the soil loaded onto the truck cannot be as densely packed as it was in the ground. Depending on the soil type, this factor usually ranges from 1.1 to 1.2. Therefore, you can expect around 400 cubic meters (cubic yards), assuming the soil is not used elsewhere on the property (since topsoil can almost always be reused for landscaping).

That’s why I said 400m3 (about 14,130 cubic feet) – the working space and slope are often forgotten in the calculations, and then people wonder why it gets more expensive later on.

We had almost a 90-degree slope on sandy soil – and in some parts of the basement neck area, there was only 50cm (20 inches) of working space. The structural builder was VERY relieved when the hole was finally closed and the occupational safety inspector hadn’t shown up yet.