Before you grout a floor, take the time to be sure that you really know what you're doing. Mistakes you make now can come back to haunt you later. A lot of people try to use wall grout, for instance, which doesn't work well and eventually cracks. What you really want top use is sanded grout. In this 4-part tutorial series, Tim Carter, of Ask the Builder, demonstrates how to mix up and use sanded grout when you're putting down a tile floor.