Therefore it is important that they cannot be opened from both outside and inside when locked. With double doors the lock case should be at least six inches in length. Where door leaves are narrow enough to prevent passage of furniture etc, consider bolting one leaf shut with a lockable bolt. Keys should never be left in locks. There should be as few as possible, kept in the possession of named responsible people.
Windows are a frequent point of entry.
Stained glass may have antique value and if well protected this may increase security. Check with your architect and the DAC about the best method of protecting windows. A Faculty will be required. External lighting acts as an excellent deterrent to the criminal. The cheapest form is high pressure sodium units with electronic timers or photo-electric switches which operate automatically.