I wouldn't think that barrel bolts would be safe on the outside. If a 2yo can open it so can a racoon. The barrel bolts we have on our coop door have a hole in the them that a padlock can be placed in. We don't need a lock yet because the door shifted and they are very hard to open. I have to bump the door with my hip while sliding the lock at same time. LOL. But if we ever get them to work right we are going to add more security.