Clean the stairs by vacuuming each tread to remove any dust or dirt, cleaning out the corners and crevices. Wipe each step with warm soapy water and a rag to remove any dirt. Wipe the steps dry with a clean rag.
Find the placement of the treads by placing a tread on a step. Center the tread by placing the center point in line with the center point of the stair. Measure the distance between the wall and the tread. Use this measurement for placing the treads evenly on the stairs. Mark the steps lightly with a pencil to show the placement of the treads.
Apply a 1/4-inch zigzag bead of adhesive, using a caulk gun, to the back of the tread, staying half an inch from the edges and covering about 60 percent of the tread. Starting at the top of the stairs, set the tread on the first step and press gently to make good contact between the tread and the stair step. Keep the tread set back from the lip of each step by half an inch.
Work down one step at a time, gluing each tread in place until you reach the bottom of the stairs. Stay off the stairs for the time recommended by the directions on the adhesive packaging.