How does one affix a mezuzah?
A mezuzah scroll is usually placed into a casing that protects it from the elements, and also beautifies the mitzvah. The mezuzah should then be affixed to the doorpost, approximately two thirds of the way up from the floor to the top of the doorpost. The Ashkenazi custom is to affix the mezuzah diagonally (approx. 45 degrees, or whichever angle the thickness of the doorpost allows), with the top facing into the room. The mezuzah should be affixed in a permanent manner, with nails, or with strong adhesive tape, to ensure that the mezuzah does not fall off of its own accord. Before affixing the mezuzah, the relevang blessing (al kevias mezuzah) should be recited.