Doorway Curtain Cuts Drafts, Heat Loss

Put a curtain in the doorway cause I feel I'm going to freeze. This isn't a CCR mashup. It's a solution I invented to combat our incredibly drafty back mud room. Drafty is an understatement. It's a frigid arctic ice station. The "walls" are a patchwork of drywall, panel, and Styrofoam, presumably for insulation. There are inch wide gaps between seams. I'm surprised the cat can't squeeze through.  Read on Put a Curtain in the Doorway Cause I Feel I Am Going to Freeze