crawl space

In the crawl spaces beside my finished attic I think I am going to add more FG insulation as I have some serious ice dams even though I have proper ventilation. On the bottom is ~2" of old rock wool with paper face down towards the lower ceiling, then about 10" of blown cellulose that is somewhere between 10 and 50 years old. Laying over that and the floor / ceiling joists is 1/2" OSB for a walking surface. (ascii diagram below) 1. Is there anything wrong with me adding a nice layer of new FG over all that old insulation? 2. Should I drill holes in the OSB to allow moisture flow from the lower insulation or should I just lay the new batts over the top? Thank you for your help! ~~~~~~~~~~~~~~ Proposed new batts ============== OSB * * * * * * * old cellulose * * * * ~~~~~~~~~~~~~~ Rock wool (paper down) _________________ =============== Sheetrock < First floor room>

We have 2 bedrooms that our furnace chimney runs between. The bedrooms have had condensation drips at the wall/ceiling joint nearest the chimney. The house also has ice dam buildups right now, and I've just started trying to figure out the problems. I was in the basement next to the furnace and felt cold drafty air coming down alongside the cinderblock furnace chimney. I'd imagine it's coming down from the attic, which means warm air can just as easily go up to the attic. How should I seal around the chimney? Should I just stuff insulation up into the floor joists that surround it? Any better ways to do it. This is just the beginning of sealing the house from the attic. I also have to seal my kitchen recessed lights, reroute my bathroom fan vent. Also am going to add a roof fan with a humidistat. Thanks for any ideas, Steve H.