What is the maximum width and thickness for a board used for schach, and can a fence plank be used that is sold loose as is and has never been attached in any fencing? thank you
Thank you for your question.
Using thin boards for schach is technically problematic, because they appear to be similar to boards that are used when making roofs, and gives an appearance of being in a regular house. This is in indeed what the Shulchan Aruch writes (O:CH 629-18, M:B 629-49). The minhag however in many places however is to be lenient with boards that are less than one tefach, since such thin boards aren’t used in roofs. A tefach for this should be measured preferably at 5cm, if not at 8 cm.
If one is stuck the Mishna Berura (ibid 50) writes that even if it 4 tefachim, that they can be used if one is stuck without anything else to use a schach, however we wouldn’t make a bracha when sitting in such a succah.
Regarding using planks that are meant to be use for a fence, I cannot comment on it without seeing a picture of it. However if you don’t have a choice b’dieved they can be used as stated above.
Have a good Yom Tov