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

Leave out the utility room in the basement, and you will achieve the same effect as saving 30m2 (320 square feet) of living space. Is a garage still planned?

jrth2151 schrieb:

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But of course, you can also combine both. You can try to have an informal conversation, get input from the general contractor (GC), and still consult a specialized lawyer afterwards.

No. There is no such thing as an informal conversation between a client who is completely stressed out because they fear for their financial survival and a GC who holds a contract and can say, "You signed it, didn’t you? Where you get the money from is not my concern."

I’ve been through this because we didn’t know for months if or how much a price adjustment would come. In that situation, you are simply not capable of having a rational conversation, believe it or not. If my very existence had depended on being unable to pay the 25,000 EUR (about 27,000 USD) price adjustment that eventually came... I don’t know if I’d even be sitting here today. Those were the worst months of my life.

In a situation like that, never go in without a neutral expert present. Especially if you want to cancel the contract or downsize the build. Because then you depend on the goodwill of the GC—accusations and a lack of objectivity are deadly.

ypg schrieb:

I thought the black bitumen coating is called a black tank. Hmm…

Not really, as you can see. Since we did not have a basement, there was quite a lot of soil to deal with—over 100 cubic meters of loose soil. We had to hurry to remove it because the neighbors wanted to start as well.
We found a buyer through eBay Classifieds, but the site was about 20km (12 miles) away, so with a truck commuting in one day, only a small amount could be moved.
Then my husband simply asked a construction company at a site, and they disposed of the soil for 2,500€. That was 10 years ago, and nowadays basement excavation would probably cost between 8,000€ and 10,000€. Maybe someone else reading can provide more precise info. Unfortunately, I don't know anyone active here who has built a basement (except for hillside constructions like @kati1337). Exactly because of the staggering costs, basements are often omitted these days.

Can share prices from 5.5 years ago: basement 55m2 (592 sq ft) with white tank: 70,000€ additional cost (we initially planned without a basement), soil excavation and removal, backfilling: 40,000€ at Z1.

xMisterDx schrieb:

No. There is no casual conversation between a homeowner who is completely overwhelmed and worried about their financial survival, and a general contractor (GC) who holds a contract and can say, "You signed it, right? I don’t care where you get the money from."

I’ve been through this because for months we didn’t know if or how much the price adjustment would be. In that situation, you are simply not able to have a rational discussion, believe it or not. If it truly had been a matter of survival for me, because I couldn’t pay the 25,000 EUR (about $27,500) price adjustment that eventually came, I don’t even know if I’d be sitting here today. Those were the worst months of my life.

In such a situation, never proceed without a neutral expert advisor. Especially not if you want to withdraw or downsize the build. Because then you rely entirely on the goodwill of the GC. Accusations, emotional reactions, and lack of professionalism are deadly there.

You should never budget too tightly. I always told GCs only about “half our budget,” so we could calmly switch to a basement redesign if needed.

Marvinius schrieb:

I can help with prices from 5.5 years ago: Basement 55m2 (590 ft2) with waterproof concrete shell (“white tank”): 70k additional cost (we had originally planned without a basement), excavation and soil removal, backfilling: 40k in zone 1.

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

That also depends on the quantity, local conditions, whether the soil is clean, how far the landfill is, and what fees they charge...

It's like saying, “What, a car for 30,000? A guy near me is selling one for 10,000!”