There was some water damage from a leak around a chimney, probably years ago before the roof was replaced. I'm going to put new boards on soon then I'll take a look next time if frosts. It was quite interesting to see, as the frost was completely melted where the two or three boards were removed (approx. 12" from drip-edge), but faded back to ice as it followed the rafters up. The middle section of the upstairs is a normal 8' ceiling and has a standard attic with insulation. You could see precisely where the attic insulation started because it was frosted just like the rest of the roof. Now I'm driving down the road looking at peoples roofs, good lord I need a hobby:)