A rim latch (Yale type) on its own is not sufficient. The door should also be fitted preferably with a 5 lever mortice deadlock, though insurance companies will accept a rim automatic deadlock; both must be to British Standard 3621 or the equivalent European Standard EN12209. Quality locks are only as strong as the doors and frames to which they are attached. Ensure that the frame is sound and the door suitable for external use; for instance, a wooden hollow core door would not be suitable. It should be of substantial construction, at least 44mm (13/4″) thick to support the mortice lock and hung on three strong 100mm (4″) hinges.
The rim latch and the mortice should be fitted 45 to 60cm (18-24″) apart. In the door itself recessed or decorative panels should be a minimum of 9mm (1/3″) thick. Consider fitting a London Bar (metal strip on frame side) to support the strike box, or Birmingham bar to support the frame on the hinge side. If the door is weak consider fitting a sheet steel plate or door reinforcer on the outside covering the lock area. Timber frames should be sound and securely bolted or screwed to the the walls every 600mm (23″) around the whole frame. Doors with glazed panels are inherently less secure than solid doors, hence the need for a deadlock. Consider replacing ordinary or toughened glass panels with laminated glass – two pieces of glass bonded together with a sheet of laminate – as they offer much greater resistance to attack.
Modern designs will usually incorporate deadlock shoot bolts or a multi-point locking system, both throwing a number of bolts from the door into the frame. Under these circumstances there will not normally be any need for additional devices. Advice on front door security while the house is occupied will vary, depending on whom you speak to. Fire Safety Officers will advise that, for safety reasons, the mortice deadbolt should not be engaged when the house is occupied, as locating and engaging the key can cause unnecessary delay in escaping from the scene of a fire. Crime Prevention Officers may suggest that a rim latch on its own is insufficient in providing adequate security and that engaging the lock would increase this, as well as the safety of young children in preventing them from wandering. Clearly these are issues which need to be considered. If you feel fire safety is the priority, additional security can be obtained by fitting draw bolts to the top and bottom of the door.