How does Weathering Steel compare to bare cold rolled metal?

Bare cold rolled metal is much less expensive than Weathering Steel and does not have the added alloy elements of Weathering Steel. Common sense dictates cold rolled steel should not be used as a roofing or siding because it is not corrosion resistant. Further, the International Building Code requires corrosion resistance in roofing materials which cold rolled steel cannot provide. It also takes on and maintains a very orange-toned oxidation, and the unstable rust formations continually break off in scales until the corrosion wears through the metal.

Weathering Steel uses expensive rust inhibiting alloy elements like copper, phosphorus, chromium, manganese, nickel and silicon. These elements clog the pores at the metal surface, forming a very tight, protective oxide finish that greatly slows corrosion.