Hello!
Yes, as the title suggests, I'm wondering what this material is

The board is light gray in color.
I'm going to repaint a house from 1916 that has been renovated in stages and had eternit in the basement and other places (I think the roof).
If this is eternit, I'm wondering how to approach the overhang, does the same procedure apply as for the facade? wash/scrape off dried paint and prime with visir before finally painting? (i.e., leave the eternit where it is)