Pictures The mishna and gemara raise more cases of dofen akuma, when the disqualified s'chach is within four cubits of the walls, we view the wall as if it continues onto the s'chach and it does not disqualify the sukkah. Air space in the s'chach disqualifies the sukkah is it covers a space of three handbreadths. There are two different versions regarding a debate about whether non-kosher s'chach disqualifies a sukkah at four handbreadths or at four cubits.