741. The Material and Measurements of the Beam and the Pole

Shabbos 17:12

The pole erected for an alley may be made of any substance, even a living creature or something from which we are otherwise forbidden to derive benefit. For example, if an idol or an asheira (a tree that was worshiped) is used as the pole, it is valid. This is because there is no minimum measurement necessary for the pole’s width. The pole must be at least ten handbreadths tall (30”) but there is no required minimum for its width or breadth.

Shabbos 17:13

The horizontal beam over an alley’s entrance may likewise be made of any substance except for an asheira. This is because there is a required minimum for the width of the beam and an asheira may not be used for any purpose that a fixed minimum measure. The beam must be at least a handbreadth wide (about 3”) but there is no minimum requirement for its thickness. The beam must be strong enough to support a brick that is one and a half handbreadths by three handbreadths (4.5”x9”). The beam’s supports must be strong enough to hold both the beam and a brick of this size.