We are building a deck that is 30″ off the ground. Local laws do not require a fence. I know there is a Halacha if Maakah. Does it apply here? If yes, does it need to be the full height (39″} or is there a shorter shiur?
30 inches is less than the minimum height to require a ma’akeh. However there is another mitzvah involved here, “Lo tasim damim b’baysacha”. We are commanded not to have something dangerous in our homes, including a place where someone can fall c”v. Even on a deck that is not technically 10 tefachim, if someone is standing at the edge and doesn’t realize where it ends, or children that may run on it etc. Therefore it needs a fence gate etc. that is high enough that it is practically safe, especially if there are children there.