The construction company is building a basement smaller than in the factory plan

Hello everyone,

a shell construction company was commissioned to build the basement from in-situ concrete according to the existing factory plan (14.0 x 6.66 m).
In doing so, the construction company missed the measurements and built the basement about 4 cm smaller. Both external and internal dimensions.

Dimensions according to factory plan
Intended house width: 6.66 m
Intended width of basement concrete walls outside: 6.525 m
Intended width of basement concrete walls inside: 6.025 m

Actual width basement concrete walls outside: 6.48 m (-0.04 m)
Actual width basement concrete walls inside: 5.96 m (-0.06 m)

I measured myself with various tape measures and a laser meter.

What should be done here?
Price reduction due to smaller total area? How much? Are there any tables or similar for this?

It is especially unfortunate that the house was built smaller on the narrow side (max. size restricted by the development plan), where every centimeter is valuable.
This has, among other things, consequences such as the factory plan possibly needing to be adjusted (staircase and adjoining walls, support columns no longer fit).

Best regards

Just for understanding: You want compensation because of a 1% deviation and are worried about having to reschedule everything?

"What is the difference between a draftsman, a concrete worker, and a bricklayer? - the draftsman works in millimeters - the concrete worker in centimeters - and the bricklayer is happy if he stays on the property!"

Basement (KG) and ground floor (EG) floor plans attached.

Just to understand: You want damages because of a 1% deviation and are worried about having to reschedule everything?

I want to clarify the legal situation. As far as I know, 4-6 cm over 6.66 m are outside the acceptable construction tolerance.

For allowable tolerances, you refer to DIN 18202 and yes, 4-6cm is too much deviation. However, no one will pay you for a dismantling because of that, and probably not for major damages either. The staircase builder will come anyway for the measurement and then build according to the actually existing dimensions. He knows that the structural builders are not very precise. And that 1-3cm of plaster will still be added to the walls, depending on the masons' mood of the day and the plasterers' temper ;)

A shell construction company was commissioned to build the basement from in-situ concrete according to the existing factory plan

Who tendered, who commissioned, and who are you anyway (builder, buyer)?

The drawing refers to the neighboring building on one hand as existing, but to me it rather looks like a simultaneously built "opposing semi-detached house." One and a half centimeters (foil ???) as insulation in between will never perfectly align between target and reality; the neighboring house would have to be built by watchmakers for that.

We know far too little about your construction project to be able to give reasonably detailed advice. But honestly, I also have more of the feeling that you are looking for support in quantifying a request for a price reduction.