Rhiannon writes from Gaylord, Michigan: "Currently, our laundry room has just the insulation hanging from ceiling and no tiles covering it. First, does this decrease the efficiency? Also, is this a violation of a building code?"

Answer: If the insulation is installed snuggly between the joists and staying in place, there should not be a problem. Not being covered does not decrease the insulation's thermal efficiency. Leaving the fiberglass insulation exposed is not a problem; it is the paper facing -- if there is one -- that must be covered with a 15 minute thermal barrier. I have not heard of this being a building code violation but I recommend checking with your local building inspector to be sure.