Things You'll Need
Construction adhesive in caulk tubes
Drop-in caulk gun
1/8-inch drill bit
12-inch torpedo level
No. 2 screw tip
3-inch finish wood screws
Fine-grained sanding block
Stair treads are an integral part of a staircase. If the stair treads are installed incorrectly the staircase will be dangerous to use. Unlevel stair treads can cause you to lose your balance and fall. Loose stair treads can slip while under load and cause serious injury. It is important that you level and securely fasten each stair tread. Replacing nails with wood screws will keep the stair treads from loosening with time. The wood screws will also hold the treads level.
Measure each stair tread. The length of the stair treads will vary at each step. Mark the length on the stair tread with a pencil. Set the table saw to make the cut. Make a jig to mark the screw locations on the stair tread.
Cut a 2-inch wide piece off of the scrap piece of stair tread that you cut in Step 1. On the 2-inch wide piece of tread, make a line 3/4 inch in from each side of the cut piece. Place a mark 2 inches in from the finished edge of the stair tread. Mark another location 3/4 inch in from the back edge of the stair tread. Extend the marks across the 2-inch face of the jig with the combination square. Drill a 1/8-inch hole at each location that the perpendicular lines cross.
Set the jig on the cut stair tread. Make sure the jig is even with the back and left side of the stair tread. Drill a 1/8-inch hole through the two holes located on the left side of the jig. Slide and align the jig on the right side of the stair tread. Drill a 1/8-inch hole in each of the jig holes located on the right side of the jig. Use the jig for each stair tread to ensure that all of the mounting screws are located in the same position.
Insert a tube of construction adhesive into the drop-in caulk gun. Cut the nozzle of the tube on a slight angle with a 1/4 inch diameter hole in the tube. Apply a 1/4-inch wide bead of adhesive to each side of the stair riser that will hold the current stair tread. Set the stair tread on the glued stair riser. Place the level, pointing front to back, on the left side of the stair tread. Level the tread. Place wood shims under the stair tread to hold it level. Use the 3-inch wood screws to secure the stair tread to both risers. Run the screws just below the surface of the stair tread. Measure the next stair tread and repeat the process until all stair treads are in place.
Fill each screw hole of every stair tread with wood putty. Sand the wood putty smooth with the stair tread surface when cured.