Got some ceramic or porcelain tiles to install? I wouldn’t install them on any of my own projects without also using an uncoupling membrane. They allow the tiles to expand and contract at different rates than the underlying floor, all without cracking or grout failure. Schluter makes the best uncoupling membranes in my experience. They call their product DITRA and you can see it in action in the video below. DITRA works for installations on top of wooden subfloors and on concrete.