Fitting an emergency-release door latch

These latches are used to prevent a child being locked inside a room. Privacy door latches with a lever handle may be fitted using a similar technique to that shown for fitting a locking latch. If the handle is a knob design, the technique has to be altered to account for cutting a large access hole in the door to deal with the locking mechanism. Most such mechanisms are opened from the outside using a key inserted into the handle. Some designs simply have a lever that can be turned, or a large slotted screw that can be turned to undo the lock. Many also have a template to follow when fitting.

Measure exact central point for access hole, on both sides of the door. If supplied, use a template.
Attach a hole cutter to a cordless drill; the correct size will be specified by the latch manufacturer. Drill into one door face
Stop drilling when the bit exits the opposite door face

Change to the opposite side of the door, drilling until the cutter reaches the cut on the other side
Drill or cut out the edge of the door to accommodate the latch mechanism
Chisel a recess for the latch plate, then fit the latch into the hole.