I'm considering a partial remodel of our basement that currently is already partially remodeled. Part of the basement once was a rec. room with paneled walls and a carpeted floor, but it looks as though there was some water damage that resulted in the removal of the carpet and some of the paneling. Since then, I've been informed that since then measures were taken to prevent a similar problem in the future, and in our three years here, we've experienced no water or moisture issues in the basement. So, since we're confident water issues don't exist, my wife and I would like to take what exists and improve it minimally so we can create a living space to store our daughter's toys and for me to watch hockey with some of my buddies.
So, with the back story out of the way, here's the question. The paneling on the wall is supported by furring strips that keep it roughly 1 inch off the wall. I would like to pull off the existing paneling, insulate behind it, and put the paneling back up. I've considered pulling everything down, reframing the walls with 2x4s and drywalling it, but it's not a space we expect to use on a regular basis and don't want to invest a ton into it. So, with that being said, would an R-6.5 1/2 inch polyisocyanurate board be enough to properly insulate the basement? I don't need it to be overly insulated, as it's not extremely cold down there as it is (we have a cast iron radiator at one end, cats iron pipes that throw off a lot of heat running the length of the room on the ceiling, and an electric space heater permanently mounted on the wall at the other end.