Originally Posted by
BillyBob58
Adding a pad adds R value , just like using a thicker quilt adds R value. If your heat output is not making it into the layers of your UQ, it must mean your heat is staying near your back instead of disappearing down below. If your pad is not thick enough to block all of your body heat from escaping below, then that heat will travel on down into the UQ in a normal fashion.
IOW, I can not see how not losing your body heat down below so that it can warm up your UQ can actually be a problem, though some will disagree with me. On the practical side, many a cold back or butt has been cured by adding a pad to an UQ. It has saved me more than once when I found out I was below the abilities of my IX UQ, and it has saved many others from a miserable night also.
One big caveat! If your pad somehow interferes with the fit and "seal" of your UQ, it might not help or might even make matters worse. I suspect, but do not know, that wider, larger ( but not thicker ) pads and very stiff pads might be more prone to that UQ fit interference. Also, do not forget the multi-use possibilities of a pad: emergency go to ground, sit pad, fire fanner, pack frame, etc etc.