There are 2 conditions for that determine which doorways require mezuzahs;
1) The room that they lead into is larger than 6.5x6.5 feet and
2) The doorway has 2 doorposts which are connected by one lintel.
Every doorway that meets the above 2 conditions requires a mezuzah, except if that doorway leads into a bathroom or shower. This includes porches, boiler rooms, outdoor sheds, attics, and outdoor gates, as long as the gate has a crossbar on top.
Work places and shops require mezuzahs as well, but if you are putting up a mezuzah in a rented office, you should do so without a blessing.