House with plinth foundation,: shouldn't the outer floor be made of thick heartwood?

[Plupp 290759]

Hello.
The house stands on high pilings against rock.
Should the outer floor that has come loose - see thin flimsy floorboards where mineral wool peeks through the gaps where damp rock lies underneath - shouldn't the floor be made of thick core wood so that the floor doesn't bend like a banana and mineral wool peeks out in the damp drafty air?

 

[Plupp 290759]

Hi.
The house stands on high piers against rock.
Shouldn't the outer floor that has come loose - see thin flimsy floorboards where mineral wool peeks through the gaps where damp rock lies underneath - shouldn't the floor be made of thick heartwood so the floor doesn't bend like a banana and mineral wool peeks out into the damp drafted air?

 

[b8q]

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