ᐅ Cost Estimate for a Basement in an Almost Shell Stage Building

Hello,

I am planning a basement and would like to know approximately what the costs might be.
-> Earthworks excluded

The key details of the basement are as follows:
- about 90 sqm (968 sq ft) of usable area with screed applied
- of the 90 sqm (968 sq ft), about 40 sqm (430 sq ft) with underfloor heating (directly next to the boiler room) – no floor covering
- no interior plaster, no exterior plaster – shell construction
- KFW40 basement standard

Ideally, it would be helpful if you could provide approximate costs for each item,
but an overall estimate would also be useful.

If any information is missing, please ask and I will provide further details.

Thank you.

The shell construction of the basement is mainly influenced by the following factors: planned construction method (cast-in-place concrete or precast elements)? Water exposure class? Room height? Electrical installation surface-mounted or flush-mounted? Concrete stairs included or excluded? Number of windows/light wells? Number of interior walls? Depending on these, you can expect costs between 750 and 900 € / sqm (square meter) for the shell construction.

Waterproofing membrane on the floor: approx. 5 € / sqm
Insulation (depending on requirements and preferences): 15-20 € / sqm
Underfloor heating: 25-30 € / sqm
Screed: approx. 22 € / sqm

For "KfW40" standards, it will definitely be important whether and how the basement area is integrated into the controlled mechanical ventilation system – you may need to plan for additional costs during the ventilation installation.

Perfect. Thank you for the assessment.

Based on your information, I arrive at approximately 87,000 EUR.

Could you please tell me what additional costs would apply if the basement were constructed as a waterproof concrete shell (“white tank”)?
The plot is on a slope (about 10%). To estimate the worst-case scenario, I would include the waterproof concrete shell in the calculation.

You will only receive a fixed price from professional companies.

I'm less concerned with a fixed price. For now, I just want to get an estimate / overview.

Building a basement to passive house standards on a slope. 90sqm (970 sq ft). Waterproof concrete plus bitumen coating. Final ceiling height approximately 2.50m (8.2 ft). Walls made of in-situ concrete. Prefabricated ceilings and a precast staircase. Two patio doors and three fixed glass panels. About 60-70% of the basement is below ground level. Shell construction costs are approximately €115,000 gross, including complete insulation – excluding groundworks. Contract awarded in February 2023. For your reference.

Best regards