Alternative lock

Thanks for writing in. First thing you want to do is to check and see if the mortise lock, or the locking mechanism inside the door, isn't broken and the primary cause of any problems you're having locking the door via the outside key lock or the inside thumb latch. To do this, remove your handle set and try manually 'flipping' the mortise lock with a flathead screwdriver. If the lock doesn't budge, then you know the mortise lock is the primary issue and needs to be replaced. See our 82-226. If the mortise lock works, then you could simply replace the outside key lock cylinder with our 82-310. If you wanted an all-new handle set, see our 82-086. Finally, I can't comment on a padlock addition to this door; that would probably require customization to the patio door itself that we don't deal in. A local locksmith may have better ideas. Let us know if you have any other questions.