A:Answer I would suggest around 10" to 12" on each side. It will also depend on who deep you are going in to the niche. If you do not anticipate going in to attach/remove cables often, you can have a lesser space on the sides. As for just getting it on the mount, you may not really need to go in deep on the sides, two persons can get it on the mount, with a little skill and care. It just snaps on and once you hear the clamps click, you are done, Do not forget to have the two cords hang down, reachable from the bottom of the tv, but just hidden behind. These are for pulling on when the tv is to be removed. What size tv you are hanging on it. I hung a 65" one.
