Unless you fit a bs 3621 night latch will require an additional lock fitted to your door to improve security such as a mortice lock.
How to fit a mortice lock to an external door.
The minimum door width is 45mm or 1 75 inches.
Fit the lock into the door and secure using screws.
A mortise lock in a very strong special locking system fitted to the inside of a door.
Difference between rim locks and mortice locks the difference between a rim lock and a mortice lock is that a rim lock is fitted on the surface of the door whilst a mortice lock is fitted in the door edge.
Step 1 measure where the lock will fit on the door.
This will be your guide when drilling.
When the mortice lock space is chiselled out insert the lock and outline the faceplate with a marking knife.
As a guide the height of your lock should be about 1 metre high step 2 using your measurement mark out both the top and bottom of the latch step 3 measure and mark out a vertical central line.
Fit the lock and check the positions of the door handle spindle and key hole adjust these if necessary.
Here are six things you need to know about mortise locks for residential door security.
Then mark and drill screw holes to fix it in place.
The body of the lock can be used as a template which you should hold against the correct position on the door and mark with a pencil draw around it carefully always keeping it central to the mark that you made.
Fit the lock back in the door so that the front plate is flush with the edge check the positions of the holes for the key hole and door handle spindle from both sides of the door if necessary remove the lock and adjust the size and or position of the holes so that they line up with the appropriate parts of the mortice lock body.
To use a mortise lock your door must be thick enough to accommodate it.
To prepare the mortice slot for the lock start by marking the centre of the thickness of the door.
Chisel away a small amount of wood at a time to open the drill holes into a clean rectangular hole to fit your lock.