65. What Requires a Mezuzah?

11:10 The minimum dimensions to obligate a house in a mezuzah is four cubits by four cubits. (An amah, or cubit, is about 18 inches, so this would be about six feet by six feet.) If the square footage is sixteen cubits but it’s not at least four cubits by four cubits (such as a rectangle two cubits by eight cubits), the authorities differ as to whether or not a mezuzah is required.

11:11 In order to be obligated in a mezuzah, an entrance must have two doorposts at least ten hand-breadths high (about three feet tall) with a lintel (the horizontal part) above them. The doorposts do not need to be separate pieces made of wood or stones; even if the walls of the house serve as doorposts and there is a ceiling over them, then a mezuzah would be required. What if there’s only a doorpost on one side, the other side being a continuous section of wall? Then, if the doorpost is on the left, no mezuzah is required; if the doorpost is on the right, a mezuzah should be attached without reciting the blessing, since this is being done in a case of doubt. Another course of action would be to attach the mezuzah on such a doorpost immediately after placing one in a doorway that definitely requires it; in this way, the doubtful doorway is covered by the blessing on the other. (This course of action is advisable in any case of a doubtful mezuzah.)