By Matthew Power. In August 1999, we wrote about Royal Building Systems ("Groundbreakers," page 134), a Canadian-based company aiming to bring its fast-track concrete housing to the United States. While U.S. builders have been slow to respond, a Mexican developer, Construcciones y Decoraciones del Sureste e Inmobiliaria, has just signed on with the Mexican subsidiary of Royal Building Systems, to create an entire community using the concrete-filled PVC forms. The planned community, to be located in Medellin, in the state of Veracruz, will include 700 homes, five stores, and several other facilities.