ᐅ How much additional cost is expected based on the structural engineer’s calculations?

Cronos86 schrieb:

That corresponds to a density of about 3.2 tons per m³ (3.2 tons per cubic meter).

Anyone who stores topsoil for 1€/m² (1€/square meter) on site will have to pay extra when disposing of it later.

Cronos86 schrieb:
540 m³ (19,080 cubic feet) is already quite a lot for a house, of course. And how 540 m³ (19,080 cubic feet) turns into 1,735 t is beyond me. That implies a density of about 3.2 tons per m³ (86 pounds per cubic foot). For clay soil, we’re usually around 1.65–1.8 t/m³ (41–46 pounds per cubic foot).

The concrete slab area was about 143 m² (1,540 square feet), plus strip foundations in some sections. Definitely not a standard reference, just meant to serve as an example for the cubic meter prices and should of course be adjusted to your own quantities. Excavation for the basement can be fairly easily estimated roughly (surface area × depth to the bearing layer + working space + slope).

You are right though, the disposal volume included removal from the driveway and construction site area, which added around 200 m³ (7,060 cubic feet) more excavation. And we actually had clay, mostly moist/wet due to the season and weather. Everything was supposed to be invoiced based on weigh tickets (theoretically) – I strongly suspect that the civil engineering sector at least partially cheats here, and I’m probably no different. But it’s hard to prove.

At that time, it was already lucky to find anyone willing to work, and everyone wanted disposal to be invoiced by weigh ticket. If invoicing by cubic meters only (possibly with a contractually agreed conversion factor) is possible, this is definitely better for cost planning – and currently, there should be a bit more room for negotiation in earthworks.

Cronos86 schrieb:

Hello,

my brief comments on this complex topic, especially since there has been a lot of discussion about waterproofing and soil excavation.

Bitumen coating + dimpled membrane (waterproofing against ground moisture, load case assessment according to DIN 18533-1:2017-07 under W1.1-E)
Waterproofing according to W1.1-E can only be done without groundwater and with well-draining soils (sand/gravel).

W1.2-E would involve the use of additional drainage even in impermeable soils without groundwater. (Here, the challenge lies in the long-term functionality of the drainage system as well as its approval.)

Black tank or white tank waterproofing must be used where there is positive water pressure (groundwater/flooding, etc.) (W2.1-E).
A black tank, as nicely summarized by Google, is a thick coating created by welding bitumen sheets. This is, of course, very different from applying two coats of bitumen paint...

A white tank is waterproof concrete. Nowadays, what is actually used is a "grey tank" (concrete with additional joint and connection waterproofing on the outside).

To assess the load case for the building, a soil report is naturally required.

The real challenge, as mentioned, is the seismic zone and the resulting requirements for basement structural engineering. As far as I know, there is hardly any way around a concrete structure there.

Regarding soil excavation, I would recommend staying calm at first. If there is a schedule, have a soil sample taken (analyses are only valid for 6 months). From August 1, 2023, the EBV (Substitute Building Materials Regulation) comes into effect, which changes quite a few things but keeps much of the core the same. If you have a groundworks contractor, have them tell you where they plan to dispose of the material and which analysis is needed. Most disposal sites and backfill operations still have their old acceptance criteria (LAGA/landfill regulations/fill guidelines, etc.). This way, you can avoid paying for duplicate analyses or being under time pressure during excavation (analysis can take up to 2 weeks).

Best regards

Thank you very much for your detailed reply!! So a black tank is indeed different from just two coats of bitumen paint—as the company also explained to me. Here it was presented as a rip-off. A soil report is already available, and it says that no environmentally harmful substances were found in this specific sample—which is good news.

Best regards

Disposal of excavated material (uncontaminated) 1,735 tons: €15,528.97

Otherwise, I suspect that around twenty thousand mentioned over the phone and twice that amount on the invoice are roughly in the right ballpark ;-)

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https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/

Lauralila88 schrieb:

Offer
as a single-family home
Plan changes from 07.01.2023
CreativHAUS Classic 143.1 including basement
 Solid construction "brick by brick" according to Building Energy Act 11/2020
 Exterior dimensions 10.63 m x 9.23 m (35 ft x 30 ft)

By the way, I can’t find this model in the HdH range, only as a semi-detached house (6.13 m x 10.67 m) (20 ft x 35 ft) (?).
What exactly did you request from them (as well as from the other two)?

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https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/

Lauralila88 schrieb:

40,000 euros for soil removal? That’s crazy! I requested a quote nearby, and they said around 20,000 euros.

It was almost 1,000 m3 (1,300 cubic yards) of clay soil due to the slope, and the backfilling with new material was included as well. Clay soil is not suitable for backfilling...