XPS same thermal conductivity - different thermal resistance

Hello everyone,

we have different XPS boards from BASF on the construction site for the floor slab:
one Styrodur 4000 CS-80 mm with thermal conductivity 0.035 W(m*K) and thermal resistance 2.25 m²*K/W
and
one Styrodur 4000 CS-80 mm with thermal conductivity 0.035 W(m*K) and thermal resistance 2.30 m²*K/W.

Two questions:
1) I strongly assume that the difference from 2.25 to 2.30 is so marginal that the two boards can definitely be mixed together and you won’t notice anything, right?

2) How is that possible? I thought if the thermal resistance is greater/smaller, the thermal conductivity would have to be smaller/greater as well? How is one the same and the other slightly higher?

Thank you very much for your answers.

Best regards

None of the people here have a clue??

1) I strongly assume that the difference from 2.25 to 2.30 is so marginal that you can certainly mix the two boards together and you won't notice anything, right?

Correct

And how can such differences occur? Doesn't one depend on the other?

Interesting theoretical question. Wasn't there also a physicist in the forum?

Have you already asked at BASF? They should be able to explain it. If they reply.