Congratulations go to Sheila Blake, Code Administrator for the City of Houston Public Works and Engineering Department, and Amanda Tullos, AIA, LEED AP, and Director of the Houston office of Green Building Services, and, of course, the Houston City Council for having the foresight to adopt such a far-reaching document. Many people worked very hard to achieve "Appendix R," and most certainly the appendix can be a model of how large metropolitan areas can respond to the social issues of affordable housing and overburdened landfills.
Every town, city, and metropolitan area in the nation has a procedure--adopted by that municipality--to ensure that new construction is done in such a way that the public health and safety are protected. Typically, this is done through the adoption of a building code, which specifies a minimum standard of protection for all construction. However, some cities go a bit beyond the adopted code and disallow some materials and procedures they deem not allowable for any number of reasons. Recycled materials usually fall into this category, since "used" materials are not consistent in quality, and could create a problem with a unified inspection strategy which would overwhelm the system.
"Appendix R," however, adopted by the City of Houston, is a guideline for designers, builders, engineers, architects, and ultimately city inspectors. It lists the kinds of "used" materials that will be allowed, predicated on considerable analysis and research. This way everyone is on the same page, and there is a unified strategy for inspecting these materials to ensure the public health and safety.