There are many different reasons that a door frame might become broken. Whether someone has kicked in your door to cause the break or it was caused by another reason, the good news is it can be repaired. There are two different ways in which you can fix the door jamb. The easy way and then the preferred way. The easy way would involve removing the damaged section and replacing it. First, cut out the damaged section. Next glue the new piece around parts that will touch the jamb that is still in place and wedge it in. Then you would apply putty anywhere that is needed, sand down the patched area, and paint the replaced section to match the rest.
The good news is that the most preferred way isn't very complicated. You can fix the frame yourself with just a few tools and a little direction. Here's how to fix your door jamb.
Removing The Seal From The Door Casing
The very first thing that you need to do in order to fix the broken door frame is to remove the caulk from around the frame. You can do this using a utility knife. Gently run the utility knife up against the molding where the caulk meets the wall. You need to make sure that you remove the caulk from the side opposite of the door as well as the side of the molding that is touching the door. Once you have done this you can use your choice of tool to very carefully pry the molding from the door entry. It is best to use a hammer or a crowbar for this.
Start at the top and pry just a bit then move to the bottom and pry and then again in the middle until the piece is able to be removed. If you find while doing this the molding breaks do not immediately panic. It is more than likely to be broken in a spot where it can be glued. Should this happen you can use wood glue to repair the break. Then use paint or caulk to fix any imperfections you find from the break.
Remove Hardware/Door Stop
Now that you have the door casing removed you need to remove the hardware from the door. Start by
taking the locks off. Later you will need the locks removed to line up the catch plate for the door and the lock for the deadbolt. You will likely only need your screwdriver to remove the hardware. There will be a couple of screws for each piece as you remove the screws you will see they easily come off. If the broken jam is the side where the hinges are then you can simply remove the hinges from the jam but leave them on the door. Set the screws and the plates and locks to the side for later. Keep them separated so that you can remember which screws go to which piece when you go to put them back on.
Some doors also have a thin piece of wood that is inside the jam called a door stop. If your door has this simply score the paint around it. Now you can use a small crowbar to pry it away from the jam. You can put this on later once you have reinstalled the hardware.
Removing The Jamb From Door Frame
If you are lucky enough to have the reciprocating saw then you will be able to fly past this step. Simply use it to cut in between the gap of the door frame and the sheetrock to remove. You need to make sure that you are careful when doing this to ensure that you do not to cut any wires that could be present. If you do not have a saw that is okay as well. You will be spending a little more time on this step but it is not impossible to complete. Simply remove all the nails or screws that are holding the jamb in place. You should then be able to easily remove the jamb.
Obtain Replacement Piece
It is time to get the replacement jamb if you didn't already have one before starting the repair. You can go to the hardware store or lumberyard and give them the dimensions that you need. Make sure that the length and the width are an exact match to the piece that you removed. Once you have this you are back on the way to putting your door frame back together.
Replacing The Jamb
You are now ready to replace the jamb. First, place the new jamb into place. Making sure that it fits right and lines up just as it should. If you find it is too long you can use a saw that you have at home and measure to cut off the extra length. Take 3inch screws and go around the frame making sure that you screw into the frame and the studs. Once the piece is securely in place you are ready to move to the next step.
Reinstall Catch Plate/Locks
Earlier you removed the hardware from the door. Now it is time to put it back on but first, you need to chisel or drill out places for the catch plate and the hardware for the deadbolt if you had one. Since the locks are already removed you can close the door and mark the jamb using a pencil placed through the hole. Once you have marked the spot you can make the holes and install the plates, as well as reinstall the door locks If the jamb that you replaced is the side with the hinges hold the door up and drill in the new screws. You will likely need some help for this part. Finally, make sure the door closes correctly and that everything lines up as it should. If it doesn't make adjustments so that it does and continue to the next step.
Finally, you can put the molding back on that you first took off. You will want to put it up and then caulk around the molding in the area where you removed the caulk from to start with. Once that is done you can paint the jamb to match the one that was damaged. Make sure that you use tape or remove the plates to ensure that they don't get paint on them.
Earlier you made sure that the door hardware was installed and that the door shut correctly. Now the door should be fully functional and the repair is complete.