Rollex Corp. claims it fabricated the first insulated steel siding panel: Thermal-Pro. Made from 29-gauge galvanized steel sheets backed with breathable expanded polystyrene, the siding resists mold and mildew and delivers an R-value of up to 2.63, the company says. That's several times the R-value of other cladding options. Thermal-Pro comes in three profiles and six colors, installs the same as insulated vinyl, and claims an installed cost comparable to fiber cement. 800.251.3300.