[If a pot] was placed on a threshold in such a way that if raised it would extend over the outer handbreadth of the lintel, and there is tumah below, inside, or above [the pot], the tumah penetrates upward and downward.  [If the pot] is one handbreadth above the ground and there is tumah below it or inside the house, [the area] below [the pot] and [the] inside [of] the house be-come tamei, but whatever is inside or above [the pot] remains tahor. [If the tumah] is inside or above [the pot], everything becomes tamei. [If the pot was placed on the threshold so that] if it were raised it would not touch an outer handbreadth of the lintel, or it is touching the side of the lintel, and there is tumah underneath [the pot], only what is below the pot becomes tamei.

[If the roof of] a house is split, [and] tumah is in the outer part, utensils that are in the inner part remain tahor. [If] tumah is in the inner part, Beis Shammai say: The split must be four handbreadths wide [for the outer part to remain tahor]; [whereas] Beis Hillel say: [It remains tahor even if the split] is very small. R’ Yose says in the name of Beis Hillel: A handbreadth.