946. A Mound Between a Courtyard and a Porch

Eiruvin 4:16

If there is a rock or a mound in the courtyard less than ten handbreadths high (about 30”), it is considered space common to both the courtyard and the porch with the result that residents of neither domain may bring things there from their homes. If the rock or mound is ten handbreadths high and fewer than four handbreadths (about 1’) from the porch, it is counted as part of the porch because they are both of a similar, elevated height. In such a case, the residents of the porch may transport objects to the rock or mound. If the rock or mound is a distance four handbreadths or more from the porch, even if it is ten handbreadths tall, it is considered part of both the courtyard and the porch since the residents of both can use it with equal ease by throwing things onto it. Accordingly, residents of neither domain may transport things to there until they make an eiruv. If a pillar four handbreadths wide is in front of the porch, the porch does not impede carrying in the courtyard because there is a division between the two domains.

Eiruvin 4:17

Protrusions from a courtyard wall below ten handbreadths are considered part of the courtyard and may be used by the residents of the courtyard. Protrusions within ten handbreadths of the top floor may be used by the people who live on that floor. The rest, which are more than ten handbreadths from the ground and more than ten handbreadths from the top floor, may not be used by either party unless they make an eiruv.