Q. We are restoring an old house with a high-ceiling cellar. I have covered the inside masonry foundation walls with 2-inch-thick Styrofoam-brand insulation. However, I have been told that the material not only is flammable but produces a dangerous gas when it burns. Is there a danger? John A. Waddington Trenton, N.J.
A. Styrofoam-brand insulation is a foamed cellular organic substance, made by the Dow Chemical Company, which contains a great many air pockets. Hence, its insulation value is high -- about R-7 per inch of thickness.
The substance may burn at about 600 degrees F. and does emit a toxic gas when burning.
Some building codes, in fact, restrict its use.
Telephone your local building department and fire chief for their appraisal and their approved use of the material in your basement. There may be a fire-retardant material which, when applied to the insulation, will make it acceptable as exposed insulation in your basement. Be sure to follow the local rules.