581. Shuttering a Window
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. 80:71 A board or something similar can be used as a window shutter even if it’s not attached so long as it has already been used in this way at least once before Shabbos, or one thought about using it for this purpose before Shabbos. (The issue being addressed here is designating something for use on Shabbos – Bi’ur Halacha 313:1 s.v. mei’erev Shabbos.) If one never used it for this before and he didn't think about it, then he may not cover the window with it on Shabbos if it's something that one might leave there for a long time. If it’s something that one would only put there for a short time, like a garment, then it may be used to cover the window in any event.
80:72 Doors and windows may not be taken off and put back on Shabbos even if they are suspended on metal hinges that make doing so easy. The reason for this is that hanging them up resembles an act of construction and removing them resembles an act of demolition.