Rockwall metal roofing recommends metal roofing for your commercial needs because it can offer upwards of 40 to 60 years of lifespan yet relatively low cost. The NAHB (National Association of Home Builders) officially rated slate by far as the roofing material with the longest life expectancy of over 150 years. clay and concrete follow the closest at 100 years. Although these roofing materials last for a long time the cost can be high.