I just re-insulated the attic in my 1928 house outside of Boston. It had 4" of old insulation under wood floor boards. I built some wooden platforms for storage, then laid down some 9" unfaced insulation under the platforms and over the wood floor. I have a hard foam insert covering the stairs leading to the attic. I don't have a ridge vent or soffit vents, so I was able to run the insulation all the way to the edge of the attic floor -- that is, I didn't have to leave a space for the air to travel up from the soffit. I have windows at either end of the attic. They have triple pane storm windows over them, so I left the screen window down and have both windows open a crack to get air circulating in the attic. (I even built a screen to go over the entire window on the inside of the attic just to make doubly sure no birds or animals poked through the window screen.) Here's my question: am I correct in leaving the attic windows open through the winter? The downstairs is warm; the attic is very cold. I think I need to keep the attic cold to prevent ice dams, etc. I don't have any other venting in the attic. No moisture (rain/snow) seems to be blowing in because of the eaves and the fact that the window is only open about 4-6". What do you think?