Does an emergency exit require a mezuzah?

Question

A mezuzah is placed on the right doorpost of the one entering the room or building.

An emergency exit is not entered from the outside and is only used as an exit -- typically to a unenclosed open area. Does it require a mezuzah? If it does, where is the mezuzah placed?

The location of a mezuzah of an enclosed deck is subject to dispute, as discussed here. However, the location of a mezuzah on a unenclosed deck door is on the right going into the house since the deck is treated as the outside and not a room of the house. An emergency exit may be completely exempt since it is not used as an entrance at all.

Answer 1

As Sam commented, the Kitzur Shulchan Aruch (11:1) addresses a nearly identical question:

אך אם יש איזה פתח שאינו עשוי אלא להכניס דרך שם איזה משא לפרקים ויש שם פתח אחר לכניסה ויציאה, אזי הפתח העשוי רק להכניס משאות, פטור

If there is a doorway that is only used to occasionally bring in items and there is another doorway that is used for both bringing in and out items, then the doorway which is used to bring in items in exempt. (translation mine)

An emergency exit is only used occasionally (for emergencies) for exit and may never be used for entry. Even if used for entry, that is also occasional and according to the Kitzur will not require a mezuzah.