Hi there,
Could you let me know if slate is good for outdoors in a place where it rains a lot?. What kind of products are recommended to install slate?.
Also, slate variates a lot in thickness. What to do when installing them? What happens if seal the tiles and grout once and stop doing it for a long time?
Thanks.

Slate is ok for wet location, but prone to cracking and splitting in areas subject to freezing. Water gets between the layers and freezes. Quartz or Quarzite looks very much like slate and is a far better choice.

Tiles get individually adjusted with more or less thinset to produce a flat floor. This can be challenging for novices.

Tiles can be washed and re-sealed at any time.