Q. In our area of Florida insulation is required in both the exterior walls and roof. All the insulating firms around here insulate standard homes with wood roofs. We would like to find a rigid insulation that can be placed before the roof is placed. The system should provide a ceiling that is at least semifinished and ready for plastering. We would be willing to settle for a two-pour system.

A. A good rigid insulation is insulating concrete, which can be mixed and placed on the job.

This can be perlite concrete, vermiculite concrete, concrete made with polystyrene aggregate, or cellular concrete. I am enclosing articles on three of these: "Perlite Roof Deck and Insulating Concrete," 3 pages, April 1961, page 95."Cellular Concrete," 4 pages, January 1963,  page 5. "Vermiculite Roof Deck and Insulating Concrete," 2 pages, March 1961, page 66.

Further information is available from Perlite Institute, Inc., 45 West 45th Street, New York, New York 10036 and from Cellular Concrete Association, 715 Boylston Street, Boston, Massachusetts 02116. Information on vermiculite concrete is available from W. R. Grace & Company, Construction Products Division, 62 Whittemore Avenue, Cambridge, Massachusetts 02140.