Mt Whitney Zone Forums General Discussion Saw most people on MR with foam pads on packs

When layering sleeping pads the R-value just is additive - so if you have one pad with an R value of 2 and one pad of an R value of 3 - that gets you a total R-value for both at 5. To be neutral on snow or in freezing temps you will want roughly a total R value of 5.5 (by the numbers - obviously each person's individual experience might adjust a bit)