A fundamental element of an eruv is the tzuras hapesach, which is defined here as, "[a] doorway opening. The construction of two doorposts and an overhead lintel." Can one make a tzuras hapesach ...
I know people do this (if there's no eruv in town, or if you're afraid the eruv will be down at the end of a 3-day yomtov); I think it involves a string from the sukkah to the house? Please explain. ...