How to Clad Concrete Steps in Stone

First, mark the center of each tread and the center of each riser with a piece of painter's tape. Mix mortar until it's thick enough to hold its shape when balled up, and trowel it onto the first step in a ¾-inch layer. Using a 4-foot level to check your work, create a mortar bed that's level side to side, with a light taper toward the front lip.