Allen writes again from Milpitas, California: "I will put this Excel data into a graph using an exponential or 1/x factor (as opposed to linear) to try to predict the R values at my 5" cavity depth.

Your competitor, Johns Manville, claims to offer fiberglass insulation that is free of formaldehyde. I was surprised it is an issue, but apparently it is sometimes part of the binder holding the fiberglass together. Can you also claim a formaldehyde free product?"

Answer: The production of Owens Corning batt insulation does include the use of formaldehyde. From the time fiber glass insulation was invented manufacturers have used formaldehyde as a binder ingredient in the manufacturing process to help glue or "bind" the glass fibers together. The trace amounts of formaldehyde found in both traditional and so-called "formaldehyde-free" insulation do not present health concerns. Owens Corning Fiberglas™ insulation is GREENGUARD Indoor Air Quality Certified® by the GREENGUARD Environmental Institute, an independent testing lab.* You can find more information on their indoor air quality testing standards at www.greenguard.org. For more on the facts about formaldehyde and insulation, click here.

* The GREENGUARD INDOOR AIR QUALITY CERTIFIED Mark is a registered certification mark used under license through the GREENGUARD Environmental Institute.