Basalt as bedding cushion or mountain gravel

Hello,

we are building a single-family house, two floors, approx. 160 sqm,
according to the soil report we have to excavate up to 1.4 m deep. In addition, a frost skirt according to DIN must be executed or frost-proof bedding under the floor slab (which is not DIN compliant).
"The construction of a frost skirt can be omitted if frost-resistant and frost-proof material, such as natural stone chippings, basalt lava or clay-free gravel, graded grain size 0/45, is installed and compacted for the necessary terrain fill."
Our general contractor recommends basalt lava or chippings (in the inquiry form for the earthworks contractor) compacted in layers under the floor slab because the soil is soft; he advises against the frost skirt due to interruptions in the bedding, which could lead to settlements.
However, basalt is much too expensive.
Alternatively, the earthworks contractor suggests mountain gravel (frost protection gravel, customary locally with report), which is also affordable.
We are now uncertain, firstly bedding not according to DIN and secondly gravel, which is mostly clayey, report or not... The foundation is probably the most important thing in construction, or are we being too critical?

What would you recommend?

Regards
Body

frost-proof padding under the base plate (which is not DIN compliant).

Who says that this is not DIN compliant?

secondly gravel, is mostly clayey,

Aha; why? When I order soil, I get this kind.

What speaks against crushed stone?

Simply placing a house on a gravel bed is often done. It is cheap, but actually botched, if above the frost-resistant depth. The DIN (there are 2-3 of them) does not really make a statement about this, so the claim that it is not DIN compliant is wrong.

The assertion that there would be differential settlements with a frost skirt is just as nonsense... you really have a great BU...

@Casper2020
The soil report states that this measure (padding) does not comply with the DIN standard EN1997-1:2009-09 / DIN regulation 1054:2010-12, p.40, and the client must be informed and must agree to it.
Gravel has not been offered to us so far, and I am not exactly sure what is meant by gravel, basalt gravel is also gravel, right?


Why is gravel padding rubbish?
Is it more sensible to install the frost apron with basalt padding? That might be even more expensive...
Regards
Body

In the mentioned standard it says, applied to your problem: "If you omit a frost apron, the padding must be frost-proof." It would only be non-DIN compliant if the padding is not frost-proof. But here lies the crux, why I say "this is nonsense," because no one can properly guarantee that this is the case, or that it will remain so.

If we have the frost apron made, can we then use gravel for the padding? The water permeability of the substrate must also be ensured.
Regards
Body