When locking your deadbolt it must fully engage into the door frame.
Deadbolts only become deadlocking when the bolt is fully extended
Because they have a spring in the bolt mechanism , that spring which is supposed to assist with throughing the bolt can work the opposite and enable the bolt to spring back in with wind or force on the door.
A simply explanation is to test the lock while the door is open.
Insert the key and turn until it until it stop ,now remove the key and try pushing the bolt back in.
It should not push in ddue to the deadlocking feature of the lock .
Now simulate a bolt not being fully engaged.
Insert the key and only partly turn it until the bolt only halfway protrudes out ,remove the key and you should be able to push the bolt back in, in otherwords the bolt is not deadlocking and unauthorized entry to your property is possible.
Call steve at Arrow Locksmiths for advice on the above.
We are a family owned mobile 24/7 day locksmithing service.