Installing a lock in the common-area of an apartment

Question: How can I tell if I can legally install a lock on a common-area door in our apartment building and still be within the fire code?

Fourchalk: Generally if there is a fire-exit sign hanging above the door, you cannot lock that side of the door. If the door in question does not display a fire exit sign, you can usually lock it. However, I must caution you that you must verify with the fire department any lock changes you decide to make to apartment common areas.