941. A Succah with a Retractable Roof

134:8 If a succah is built with a roof that opens, it should be opened before placing the schach, then closed and re-opened. This does not affect the validity of the schach as it's no different from spreading a covering over the succah and then removing it. One must make sure that the roof is open when yom tov begins. One must also be careful with such a succah that the roof is fully open and standing in line with the walls. If they are not properly vertical,  but leaning in a little over the schach - even by an amount that will not invalidate the succah - one must still be careful not to sit in a place that is overshadowed by the roof. Even though a booth built for Succos does not require a mezuzah, an identical structure built for use throughout the year does. The holiday does not exempt such a structure from requiring a mezuzah; therefore, there is no need to reattach the mezuzah from scratch after Succos.

134:9 One can fulfill the mitzvah with a borrowed succah but not with a stolen succah.  Therefore, one should not build a succah in a public place (since those who observe Succos do not have exclusive rights to the land - see Mishnah Brurah 637:10). In an emergency, if no other succah is available, one may sit in such a succah and recite the bracha.