This is because inferior materials are often used by roofing contractors. The reason for this is either because of ignorance or greed. The roof flashings (valley, roof to wall, chimney, etc.) are usually supplied by the same building material supplier that supplies the shingles. While shingles have improved, the steel flashings used on roofs have not. They are typically a baked enamel finish or raw galvanized steel and will start rusting in as little as 5 years. When shingles used to last 10-20 years, this was not a problem. Now shingles can last 30, 40, or even 50 years. Beware – your contractor knows you probably do not have any idea that there are options in the roof flashings used on your house. And they will take advantage of that. Ask questions – Is the flashing 26 ga. or thicker (the lower the number, the thicker the steel)? Is the paint finish a commercial finish like Kynar 500 or SMP? Are the roof flashings being supplied by a sheet metal shop like GSB Services or is the supplier delivering it with the rest of the roofing materials? A ‘yes’ answer to this means you are getting inferior materials for the most critical parts of your home’s roof.