ᐅ Is basement insulation necessary, general contractor or earthworks specialist?

Hello everyone,
we are building an urban villa with external dimensions of about 10m x 10m (33ft x 33ft). The basement has a clear room height of 2.5m (8ft).
Because of the sloped site, the costs look like this:
- Usable basement: €67,800 (Glatthaar)
- Frost protection strip, 17.5m (57ft): €3,770
- Perimeter insulation, 14cm (5.5 inches): €5,275
- External thermal insulation composite system (ETICS) on the exposed basement walls: €5,178
- Scaffolding on the exposed basement walls: €1,000
- Thermal insulation, 10cm (4 inches) underneath: €7,260
- Relocation of heat pump into the basement: €2,100, ventilation: €3,400

We have installed underfloor heating in the house. The basement was planned without heating due to costs. Currently, we do not require living space in the basement.

Questions:
- What do you think about the costs and the proposal from my general contractor?
- I have considered removing the insulation and arranging it directly with the earthworks contractor. How advisable is this (warranty, mold risk, scheduling / coordination issues…)? Who did the insulation in your projects?

Thank you for your answers.

I find the whole thing a bit questionable. You are insulating your basement and will likely keep it within the thermal envelope. If you don’t heat the basement directly, then you are effectively heating it through the first floor above. In my opinion, the heating system should also be installed directly in the basement. The rooms don’t necessarily need to be maintained at living room temperature.