When I have a client who is buying a home. I strongly recommend that they replace the entry door knobs and deadbolts on their home as soon as reasonably possible. There is no way to know who the previous owners have given a key to. For personal safety alone, this is a task that should not be delayed.
Types of Cylindrical Door Knobs
Privacy lock (aka bedroom) – has a button or thumb turn on the inside knob, which locks the door so it cannot be opened from the outside.
Passage (aka closet and hall) – cannot be locked and is typically used on closets and hallway doors.
Keyed Lockset (aka entry) – can be locked or unlocked from both sides of the door by usin g a key, a button or a throw latch depending on the type.
Dead bolt – This is an auxiliary lock that is used to improve security. A double cylinder dead bolt requires a key on both sides of the door to lock or unlock the door.
Keyed Alike – this is when all locksets and deadbolts use the same key to lock/unlock. When replacing locksets/deadbolts on more than one exterior door you can purchase multiple sets that are keyed alike. Look for matching numbers on the back of the packaging.
Steps to Changing a Doorknob
1. Detach the trim or rose (the ring of metal between both doorknobs and the door) by removing the two screws that hold it on. In newer doorknobs, this does not exist.
2. Remove two more screws under the trim. These are long screws that attach the two doorknobs on either side of the door.
3. Pull the doorknobs apart and remove them from the door.
4. Remove the two screws that hold the bolt (the locking mechanism), which remains attached to the door, and extract the bolt or throw.
Note: If you are replacing your doorknob with the same brand, you may not need to change this portion out.
5. Look at the metal strike plate attached to the frame around the door (this is what catches the bolt). If the strike plate is not loose and is the right color, leave it there. Otherwise, detach it by removing its screws.
6. Insert the new bolt into the door and screw it into place. Remember to face the slanted side toward the direction the door closes.
7. Insert the doorknob on both sides of the door, making sure the two are aligned so that the long screws can hold them together.
8. Tighten the screws gradually, alternating each one so that the doorknobs come together evenly.