You want your attic space cold and well ventilated in the winter. Ice shield and heat trace on the eaves is a good idea to prevent ice damming. Frost is caused by the heat going thru the upper ceiling and going thru the dew point in the attic space. Good insulation and ventilation keep the top of the ceiling surface at, or below, freezing.
Another issue that I'm having a hard time with (and seems to be the rage with energy auditors) is a sealed crawl space under the house. No foundation vents and then a air "conditioning" system. And I don't mean cooling, but a humidity control and/or air exchanger. Anyone run one of these and have an opinion?
