If a board was placed over the mouth of a new oven and it extends from all sides by a handbreadth's space, if there was impurity underneath it, vessels that are on top of it remain pure. If there was impurity on top of it, vessels beneath it remain pure. If it was an old [oven], they are impure. Rabbi Yochanan ben Nuri declares them pure. If it was placed across the mouth of two ovens and there was impurity between them, they are impure, but Rabbi Yochanan ben Nuri declares them pure.

If an oven screen [which is not able to become impure] was placed over an oven which was sealed, if there was impurity beneath it or on top of it, everything is impure. But opposite the airspace of the oven is pure. If the impurity was opposite the airspace of the oven, everything opposite it up to the firmament is impure.

If a board was placed over the mouth of an old oven and it extends from both ends a handbreadth but not on all sides, if there is impurity on one side, vessels on the other side are pure. Rabbi Yossi declares [them] impure. A windowsill does not spread impurity. If there was a protrusion, Rabbi Eliezer says it does not spread impurity but Rabbi Yehoshua says we view the windowsill as if it were not there, and the higher protrusion does spread impurity.

If the sandal of a cradle made an indentation in a house, if it had a handbreadth's space, everything is impure, but if not they count from it as they would from a dead body.

The beams of the house and the upper story which do not have plaster on them and they are aligned, if there was impurity underneath one of them, underneath it is impure. [If it was] between the lower and the upper one, between them is impure. If it was on top of the upper one, opposite it up to the firmament is impure. If the upper ones were as if between the lower ones and there was impurity under one of them, underneath all of them is impure. If it was on top of them, opposite it up to the firmament is impure.

If a beam was placed from one wall to another wall and there was impurity underneath it, if it had a handbreadth's space, it spreads the impurity underneath all of it. If not, the impurity pierces and goes up, pierces and goes down. How large must its perimeter be for it to have a handbreadth's space? When it is round, its perimeter must be three handbreadths. When it is square, four because the square is larger than the circle by a quarter.

A column which was standing in the open air, if it has twenty-four handbreadths in its perimeter, it spreads impurity underneath its sides, if not the impurity pierces and goes up, pierces and goes down.

If [a piece the size of] an olive of a corpse was stuck to a threshold, Rabbi Eliezer declares the house impure, but Rabbi Yehoshua declares [it] pure. If it was placed under the threshold, it follows the rule of half and half. If it was stuck to the lintel, the house is impure, Rabbi Yossi declares [it] pure. If it was placed inside the house, one who touches the lintel is impure. One who touches the threshold, Rabbi Eliezer declares [him] impure but Rabbi Yehoshua says from a handbreadth down, he is pure, from a handbreadth up, he is impure.