Sukkos in Multi-Story Buildings
Question: I live in a multi-story apartment building, at a height of more than twenty amos from the ground.73 May I build my sukkah on the porch outside my apartment, or must I build it on the street so that it is within twenty amos of the ground?
Discussion: The sukkah may be built on the high porch. The twenty-amah limit is measured from the sukkah floor, not from ground level. Therefore, even a sukkah on a very high floor can be valid.
Question: Are there any other concerns regarding sukkos in such buildings?
Discussion: Actually, building a sukkah on a lower floor can involve greater concern. Very often, there are protrusions from a higher floor, which can sometimes be too high for one to notice without paying attention. Common examples include balconies, air-conditioning units, protruding window bars, a series of clotheslines, and overhanging roof.74 As a rule, sechach that is underneath something that is invalid for sechach is rendered invalid.75 However, how this will affect the sukkah — whether it may be disregarded, will disqualify the area beneath it, or even disqualify the entire sukkah — will depend on many factors. This complex subject is discussed at length in Chapters 626 and 632. Should it be relevant, one who is not thoroughly proficient should consult a competent halachic authority.
73. Twenty amos is the maximum height acceptable for a sukkah (Shulchan Aruch 632:1).
74. Note: Sechach protruding from a sukkah up above is not a problem in most cases. Although a sukkah under a sukkah is invalid, that is only if it is under a valid sukkah with proper walls; a bit of protruding sechach is not considered a ‘sukkah’ and does not therefore invalidate a sukkah underneath it (Sha’ar Hatziyun, 628:5).
75. Shulchan Aruch 626:1.