Mezuzah Facing Outward

Question:

I always try to put my mezuzot on the wooden doorframe rather than on the wall of the opening. But in my new apartment the doors fill up the whole wood frame, and the mezuzot would have to be put on its outer side, facing out? Even though they would still be within the opening, would it be better to put them on the concrete so that they can face the right way?

Answer:

As long as the mezuzot are within the doorway, they can face in any direction.[1] However, placing the mezuzah outside of the doorway is unacceptable to many authorities. And even those who allow outside placement state that this option is far from ideal and should be avoided when possible.[2]

[1] Agur B’ohalecha 14:4.

[2] Agur B’ohalecha 14:12.