During Succot, we were discussing what materials may be used to secure the schach. Most people that I know, including I, use a bamboo mat and lay some planks of wood on top to secure it down.
Someone in my shul asked if the mat may be laid down in a "wavy" fashion. For example, let's say one lays bamboo poles on top of the succah in a fashion such that some poles are under the schach mat supporting the weight of the mat underneath, while other poles are on top of the schach mat securing it down against the wind. Thus, when viewing the mat from the top of the succah, it is not completely flat but you would see parts over a pole and parts under it like a "wave" pattern. Is this OK?
The answer below does seem to address that as long as there are distinguishable walls, this arrangement is fine. However, I am curious if there's any concern for using a "mixed schach arrangement" like this. I.e., some bamboo poles are used for "support" (the ones under the mat) and some used on top of the mat (which, I guess, would be considered the "roof" or actual "schach". So, one possible concern is - if the supporting poles are considered halachically "schach". Why does this matter? Let's say a wind blew off the mat with the poles on top of it but the poles that were underneath that had supported the mat stayed there.
