Ohalos 6:4-5

Ohalos 6:4

If there’s a wall between two houses and something ritually unclean is inside it, then the house closer to the impure object is rendered unclean while the house closer to the clean part of the wall remains ritually clean. If the impurity is in the middle, then both houses are rendered unclean. If there’s something ritually unclean in one of the houses and utensils inside the wall, then those in the half closer to the impurity are rendered unclean, while those in the half closer to the ritually-pure house remain clean; any utensils in the middle are rendered unclean. Let’s say there’s plaster between the main floor of a house and its attic and there’s something ritually unclean in it. If the impurity is in the lower half of the plaster, the house is rendered unclean and the attic remains clean; if it’s in the upper half, the attic is rendered unclean and the house remains clean. If the impurity is in the middle, then both the house and the attic are rendered unclean. Let’s say that the impure substance was in either the house or the attic and there were utensils in the plaster. Those in the half closer to the impurity are rendered unclean, while those in the half closer to the pure area remain clean. If the utensils are in the middle of the plaster, they’re rendered unclean. Rabbi Yehuda says that all the plaster counts towards the attic.

Ohalos 6:5

Let’s say there was something ritually unclean between the rafters and beneath it was covered with something as thin as a garlic skin. If the impurity was in a cavity a handbreadth in size, then everything is rendered impure. If there isn’t a space of a handbreadth, then the impurity is considered like a solid block. If the impure substance was visible from inside the house, then the house is rendered unclean regardless of whether or not there was a space of a handbreadth.