I have no experience with this, but I just installed some. You can get them with the same pattern in different thicknesses. In the store the 1/2" thick tiles (non-"fire-rated", ~$40/case?) would bow when you picked them up with two hands right out of the box. The exact same 2'x4' tile size and pattern, but "fire-rated", and 5/8" ($60/case) was much better. I don't know if it was just the thickness that made them "fire-rated". I'm not sure of the prices, or if they are available in cheaper non-"fire-rated" in 5/8" thickness too. I'm talking about Armstrong tiles at HD, and the random-textured pattern which can be cut in any direction from looking at it. However I have no idea if the 5/8" fire-rated ones will sag eventually over time.