579. An Intermittent Doorway

In an introductory note to this chapter, the Kitzur Shulchan Aruch writes that most Jews are already familiar with the prohibited labors of Shabbos and that he is only addressing common situations with which people may not be familiar. Clearly, the laws of Shabbos constitute an area requiring much greater study than this email alone will allow. 80:67 Just as we may not erect even a temporary structure on Shabbos, we may likewise not add even a temporary addition to a permanent structure. Let’s say that a building has an opening that is not designed for regular entrance and exit, being used for this purpose only intermittently. Let’s also say that one made a door for this opening, and this door doesn't swing on a hinge but rather it is attached so that it just hangs there to close the opening. If the door has a hinge, or even if it used to but it broke off and left a mark showing where it was, one may use this door to close the opening on Shabbos. This is so even if opening it causes the door to drag on the ground and if closing it requires one to pick the door up and set it in place. The reason this is permitted is because the door is attached and it hangs in the opening, plus it has the signs of a hinge, which makes it recognizable as a door for opening and closing and not an act of building. This is all the more permitted if the door in question has a hinge. One may not, however, re-attach the hinge to the doorframe, as this would be an act of construction.

80:68 If the door in question does not have the sign of a hinge, one may not close an opening with it on Shabbos. Since this opening wasn’t designed as an entrance except intermittently, and since the door is not clearly recognizable as such, closing it resembles construction. However, if it is attached and well suspended so that it doesn't drag on the ground when opened, even if it’s no higher than a hairsbreadth from the ground, then it is recognizable as a door and one may close the opening with it on Shabbos.