1,183. "A Succah Inside a Succah"

Hilchos Shofar, Succah v’Lulav 5:23

If the canopy of a bed in a succah is higher than ten handbreadths (about 30”), then one who sits under it does not fulfill his obligation because it is considered a succah inside of another succah. The same is true of any canopy as large as a handbreadth (about 3”); if it is ten handbreadths high, one may not sleep under it in a succah. Similarly, if one erects four pillars and spreads a sheet over them, if they are ten handbreadths tall, it is considered a succah inside another succah.

Hilchos Shofar, Succah v’Lulav 5:24

Conversely, if a person spreads a sheet over two pillars or uses a canopy with a roof that is less than a handbreadth wide, one may sleep under them regardless of their height. Such a structure is not considered a succah inside a succah because it doesn’t have a roof.