First mark out the place where the strike plate has to be fitted.
How to fit a internal door lock.
Hold the door latch against the face of the door flush with the door edge and mark the spindle centre on your previously marked centre line see fig 1.
In some cases door latch plate mortises might need to be cut or enlarged.
Place a wedge at the bottom of the door to keep it in place.
Begin by removing the screws from the door knob on the interior side of your door.
Mark out the strike plate on the door frame after you ve fitted the lock in the door you need to fit the strike plate to the door frame.
Turn the key so the locking bolt protrudes from the lock and hold the door against the door frame.
Fit the wedge into the bottom of the door as close to the wall as possible.
Using a square mark this centre line for approximately 4 100mm on the face of the door the pencil mark can be removed later with an eraser or damp cloth.
Create a mortise for the plate around the latch on your door using the technique described above.
Remove the two screws from the latch plate on the edge of the door and remove the latch from the opening.
If the knob is to the right select a right handed door.
Open the door and stand with your back to the hinges.
Then use a drill to make the necessary holes for installation of your doorknob door handle and lock.
If the doorknob is on the left you need a left handed door.
Shake the door a bit to make sure it is secure.
This video is about how to fit a door latch and door handle in an interior door.
Purchase a door stop or professional grade door wedge from a local hardware store or from an online retailer.
Tools needed for this job.
Create a mortise and holes for your lock and door handle.
This allows you to pull the door knobs off the door from both sides.