The show opens at Casa Cordova, one of the last remaining pieces of early Tucson. Built in 1848 within the original presido (""walled fort"") walls, the Casa is now preserved as part of the Tucson Museum of Art. At the job site, the crew arrives to find progress well underway.Genreal contractor John McCaleb inspects termite and honeybee damage with continuing on to the new addition, whose walls are complete, put up in four days by a two-man crew using hollow building blocks made from recycled styrofoam and concrete. With rebar added horizontally and vertically and concrete poured in, the new walls achieve a remarkable R-36 rating. Then we visit the magificent Catholic mission San Xavier del Bac, built in the late 1700s and now undergoing extensive renovations, some of which incorporate prickly pear juice! Then it's back to the house where plumber Dan LaBlue is using flexible plastic (PEX) tubing instead of copper for the building' water supply. The plastic tubing is nearly approved fo