New doorknobs will give an updated look to your home's doors. Before you shop for a new knob, grab a screwdriver and remove the knob you want to replace (learn how in the following slides). Removing the knob before you shop will give you a sense of what type of replacement knob you'll need. You might even want to take the old knob to the store with you for comparison.
To remove a doorknob, the only tool you will need is a Phillips screwdriver (the one with four ridges that come to a point like a pyramid). Start by removing the two screws that hold one side of the old knob into place. For some knobs you will need to remove screws from the other side, too.
Both knobs should come off along with the plate that covers the hole in the door. A square steel peg that connects the two knobs and slides into a square hole in the latch will most often come out with the knobs.
If the latch stays in, simply slide it out. Some latches will slide out the edge of the door with just a little bit of persuasion. With most you will have to remove the two screws that attach to the edge of the door.
Remove the two screws that hold the strike plate to the door frame.
Measure the distance from the center of the big hole in the surface of the door to the edge of the door. This distance, known as backset, typically equals 2-3/8 inches or 2-3/4 inches. Many replacement doorknobs will work with either backset, but be sure your new knob is designed to work with your measurement.
Tip: If you are purchasing a knob with a lock, you will want to know which side of the door the locking mechanism is on before you buy a new knob. Doorknobs are not reversible. If you want the lock on the inside of a room, you need to note if it is to the left or right when the latch is facing you.
Start the installation by determining the style of latch plate you need. Depending on the mortise (the cut-out impression the latch sits in) on your door, you might have to swap out the latch's standard rectangular plate for a round one included in the package. If needed, pry off the standard one with a straight-bladed screwdriver (see left and middle photos) Then, place the new round plate on the latch (right).
Slide the latch into the edge of the door. If it has a rectangular plate, you’ll need to attach it with the two provided screws.
One half of your new doorknob will have the square steel peg. Insert that half into the door first, placing the square peg through the latch mechanism.
Align the other half of the doorknob with the square pin and the screw holes.
Attach the new knob with the two screws included with the knob set. If the new doorknob does not cover the screw holes, mortises, or any impressions left by the old hardware, it’s time to break out the wood putty. First, sand down any surface imperfections and fill screw holes and excess mortise areas with a hardening-type wood putty. You can try touching up the affected areas with stain, clear finish, or paint—whatever the door and frame requires—but if that doesn’t blend colorwise, you’ll need to refinish or repaint the entire door or frame.
Attach the new strike plate to the door frame with the two screws provided. If you need to enlarge the mortise for the latch plate or the strike plate, make sure you have a sharp chisel and fresh blade for your box cutter. To enlarge the mortise, first define its outer edges with a box cutter. Then position the chisel to remove the excess material.
You now have a new doorknob. And now that you know how quick and easy a doorknob change can be, updating all the ugly and/or broken knobs in your home will be a cinch.