Question: What thickness do I need if using Travertine Tiles over concrete outside?

Answer: Installed on concrete, Travertine Tiles need to be 3/8" or 1/2" thick. 

Tiles must be mortared and not sand-set (unlike Travertine Pavers, which can be installed on top of gravel/sand). Travertine Pavers are 1.25" thick.