ᐅ Additional cost for waterproof concrete basement (WU concrete cellar)

Our soil survey showed that we need to waterproof our basement against hydrostatic pressure.
The additional cost quoted for this is quite significant.
What is a typical surcharge per square meter compared to a standard basement for something like this?

This varies significantly by region.

I can’t provide a direct comparison, but I suggest contacting 10-20 companies to request quotes for a waterproof concrete basement with exactly the same specifications as your current provider.

That way, you’ll get a realistic idea of prices in your area. You still have the final say about which company you choose to work with.

Why was the quote so much more expensive?
What is the size of your floor area?

So, the floor area is 140 sqm (1507 sq ft) and the wall area in contact with the ground is about 110 sqm (1184 sq ft). The additional cost for this is 25,000 EUR. That almost knocked me off my chair.

Compared to a masonry basement or a poured concrete one?
A waterproof concrete tank (white tank) would be about 23,000 more expensive for us than a masonry basement, calculated for 100m² (1,076 sq ft) of floor area without exterior walls.
I can recommend asking a basement specialist. You might get a better offer that way.

If the extra cost is for masonry and takes the size into account, I don’t find that unreasonable.