This historic digest is part of a series published by the U.S. Department of Commerce’s National Bureau of Standards on the technical characteristics of building materials used in the construction of affordable housing units. Each digest presents condensed, essential facts regarding its given topic, and is intended for use by staff at federal agencies, manufacturers, trade associations, and builders. This publication presents a summary of several National Bureau of Standards research papers and circulars, and is an update of a previous digest on the same topic.

This report is part of the collection of scanned historical documents available to the public.