Chapter 11:1-3
The Mitzvah of Mezuzoh
1. It is a positive commandment to affix a mezuzoh to every doorway in
one's home. Even if one's home contains several rooms, and each room
contains several doors made for entrance and exit, a mezuzoh is required
for each of them. This applies even when one ordinarily uses only one of
them.
Furthermore, even if the number of people living in the home decreases and
there is a need for only one entrance, it is necessary to affix mezuzos on
all of them. However, if one doorway is used only to bring in packages
from time to time, and another doorway is used for coming in and going out,
there is no obligation concerning the doorway used to bring in packages.
2. Gates to courtyards, alleyways, cities, and countries require mezuzos,
as [Deuteronomy 6:9] states: "and on your gates."
3. The mezuzoh must be affixed on the doorpost at a person's right side as
he enters. If it is affixed on the left, it is unacceptable and must be
removed and affixed on the right side. The blessing must be recited when
correcting this error. In this regard, there is no difference whether one
is left-handed or not.