Things You Will Need
Power Miter saw, Hammer, Tape measure, Power screwdriver, Drill & bits, Stud Finder (electronic recommended), Chalk line, Marking pencil, Four foot level, New handrail, Handrail brackets, Wood glue, 4d Finish nails
Begin by measuring from the nose of the top landing to the nose of the bottom stair tread and add two feet. The extra length is for the returns you will cut for each end and to allow for possible cutting errors. The length will also determine how many mounting brackets will be needed. Brackets should be mounted every 48 inches but at a minimum at both ends and the middle of the handrail. The new handrail and mounting brackets can be purchased at your local lumber yard or home center.
Determine the placement height of the new handrail based on the local codes and your comfort level within the acceptable range. Place the new railing on the steps and measure diagonally the distance from the top of the rail to the bottom. Then measure the distance from the top of the mounting bracket to the bottom screw hole on the bracket. These combined measurements are the distance from the top of the rail to the location of the bottom mounting screw. Subtract this distance from the mounting height of the handrail. Place a mark on the four foot level equal to the calculated measure. Place the level at the nose of the first stair tread and holding the level plum, put a mark on the wall. Repeat this at the nose of the top stair tread. Run a chalk line between the two marks. Along this line is where you will pre-drill the holes for the bottom screws of each mounting bracket.
The next step is to locate the studs in the wall. The brackets have to be securely mounted to the wood framing or the handrail could pull away from the wall and become a safety issue. Using the electronic stud finder, mark each side of each stud. Starting with the bottom bracket, pre-drill a hole for the center bracket screw along the chalk line at the center of the wall stud near the bottom of the stairway. Mount the bracket with the bottom screw. Pre-drill the other two holes on the bracket with a slight angle toward the center of the wall stud to ensure that the screws are going into solid wood. Install the two screws. Repeat this process near the top of the stairway. The middle brackets will be mounted after the handrail is attached at both ends.
Place the handrail on the stairs and mark the handrail approximately one inch back from the edge of the nose of bottom stair tread. Mark the other end of the handrail approximately one inch from the back of the top stair tread. Cut both ends at a 45 degree angle with the angles facing the wall. The cut off pieces will be used for the opposite end returns.
Mount the handrail to the top and bottom brackets and measure the distance from the long point of the 45 degree miter on the rail to the wall for the length of the returns. Cut the returns to size. Drill pilot holes and nail and glue the returns to the ends of the handrail using 4d finish nails and wood glue. Locate the center brackets and attach them to the wall studs and the handrail in the same manner as the top and bottom brackets.
You are now ready to apply finish to the handrail. You can paint, stain, or just clear coat the handrail. It would probably be easier to remove the handrail to apply the finish and, since all the holes are drilled, remounting the handrail will be easy.
A strong, well mounted handrail makes stairways safer for everyone and it is not as hard as it may seem to install one.
Tips & Warnings
Whenever working with tools, safety glasses are recommended. Masks are also recommended to be worn when working with some types of wood and wood finishes or paints to protect your lungs.
Working with power tools can be dangerous. Always use caution and pay attention at all times.