A protrusion spreads impurity in any size, a balcony and a canopy with a handbreadth's space. What is a protrusion? That which has its face [surface meant for use] down. And a balcony? That which has its face upward. When did they say the protrusion spreads impurity in any size? When the protrusion is three rows of stones above the opening which is twelve handbreadths. More than that, it spreads impurity with a handbreadth's space. Crowns and engravings spread impurity with a handbreadth's space.

A protrusion which is on top of a doorway spreads impurity in a handbreadth's space. One on top of a window two fingers high or on top of the thickness of a drill, [spreads impurity in a space that is] any size. Rabbi Yossi says [it spreads impurity in a space that is] its [the window's] thickness.

A reed which is above an opening, even if it is one hundred cubits high, it spreads impurity in any size, says Rabbi Yehoshua, but Rabbi Yochanan ben Nuri says, it should not be treated more stringently than the protrusion.

A protrusion which surrounds the whole house and extends into the opening three fingers, if there is impurity in the house, vessels underneath it are impure. If the impurity were beneath it, Rabbi Eliezer declares the whole house impure, but Rabbi Yehoshua declares [it] pure, and similarly with a courtyard that is surrounded by a colonnade.

Two protrusions one on top of the other, and they have in them a handbreadth's space and between them a handbreadth's space, if there is impurity beneath them, what is beneath them is impure. Between them, what is between them is impure. On top of them, opposite it up to the firmament is impure. If the upper one extends over the lower one by a handbreadth's space, if the impurity is beneath them or between them, what is beneath them and between them is impure. On top of them, opposite it up to the firmament is impure. If the upper one extends over the lower one by less than a handbreadth, if there is impurity underneath them, what is underneath them and between them is impure. If it was between them or underneath the extended part, Rabbi Eliezer says beneath them and between them is impure but Rabbi Yehoshua says, between them and underneath the extended part is impure but underneath [both of] them is pure.

If they had in them a handbreadth's space but between them was less than a handbreadth's space, if there was impurity beneath them, what is beneath them is impure. Between them or on top of them, opposite it up to the firmament is impure.

If they did not have in them a handbreadth's space, whether there was a handbreadth's space between them or whether there was not a handbreadth's space between them, if there was impurity beneath them, between them or on top of them, the impurity pierces and rises, pierces and goes down. Similarly, two curtains which are a handbreadth's space above the ground.