Michelle writes from Freedom, Pennsylvania: "My house was built in 1980, typical Pennsylvania 2-story colonial box house. The attic has blown-in insulation with just the exposed joists (no flooring ever added). It has always been very cold upstairs (bedrooms) and a normal temperature downstairs (living area). Can I put the rolled fiber glass insulation on top of the blown-in insulation? I worry about a fire hazard, plus I wouldn't know what R factor to purchase. There's approximately 8 inches of blown-in insulation, I guess that's called cellulose? Reminds me of shredded newspapers."

Answer: Yes, from your description it does seem to be cellulose. I do not have a depth-to-R-Value chart for that product because Owens Corning does not manufacture it. To answer your question: Yes, you can roll fiberglass insulation over it. Keep in mind that compressing the existing insulation will cause a loss in R value. Either the weight of the new insulation or foot traffic while installing may affect the blown-in insulation's R-Value. I recommend having the new insulation blown in to avoid such problems.