If an electric garage door opener has been installed on your door, it may not be necessary to have a lock. Properly installed, electric openers can function as the lock, making it improbable that an intruder would be able to lift your door from the outside. If you have an older opener, check to see if your door can be lifted from the outside.DASMA, the trade association for the garage door industry, discourages homeowners from attaching a lock when an opener has been installed, because too frequently, a child or other family member will accidentally lock the door. If someone then tries to open the door using the electric opener, the opener will pull against the lock causing the door to be damaged. If no opener is installed on your garage door, a lock is highly recommended.