[chacam]

I installed tile on our lanai just using thinset. The lanai wasn't a brand new pour but a few years old. I figured that if it was going to crack, it would have done so already. No problems yet. The lanai was open and I did drill a few holes down through the grout over the saw cuts to allow water to drain, then the following year, we enclosed it with sliding acrylic windows. Good luck.