Thanks to everyone for their ideas... bc, to answer your ?s: I do have bathroom fans which are vented to the soffit through insultated ducting. I have seen icicles by the soffit vent on outside of house, so moisture is making it there. I do have a fireplace that gets intermittent use & I crack a nearby window while fire is burning. As far as insulation, I have kraft paper faced R-11 fiberglass batts with several inches of cellulose blown in over the top of it. The cellulose insulation is quite wet in places, I don't think it will ever dry out.