Metal Roofing by the Sea In 2010, 123.3 million people lived in U.S. coastal counties according to a report by the National Oceanic and Atmospheric Administration’s (NOAA) Office for Coastal Management. That’s a lot of people who require a lot of residential structures, which need a lot of roofs. Faced with salt spray exposure and hurricane-force wind and rain, more and more seaside homeowners are choosing metal roofing due to its hardiness, longevity and proven track record along the coast. NOAA also states that, annually, coastal counties produce more than $8.6 trillion in goods and services – the businesses producing this money are housed in commercial, industrial, agricultural or residential buildings, which also need roofs. With 22 states boasting saltwater coastline, the U.S. roofing market requires solutions that can stand up to this often-harsh environment. Here are areas to consider when bidding a metal roofing job by the sea.
Travis Lord, Product Manager for The Garland Company, said, “When on the coast, typically the go-to will be .040” or .050” aluminum. Stainless steel and zinc are also great options but tend to be more expensive. Aluminum is more cost-effective than stainless steel and zinc and still does a superb job at handling salt-spray environments.” He recommends avoiding galvanized steel as it can rapidly corrode in a coastal environment. Drexel Metals’ Director of Sales, Ken McLauchlan, added that while aluminum is more corrosion-resistant than steel (and is lighter), it is also softer. The entire roof system will be less of a load on the structure but won’t stand up to the punishment of a severe hailstorm as well as steel. Natural metals are often said to perform best, as shared by Robin Anderson, Technical Manager for Boral Roofing, who noted about each metal type:
Aluminum: Though highly corrosion-resistant, also does not have the strength of steel. Warranty and performance to winds may be lower than other materials. Patina of aluminum oxide will dull the bare color. Zinc: Though highly corrosion-resistant, does not have the strength of steel. Warranty and performance to winds may be lower. Patina darkens the coloring and the cost is high. Anderson also added that alloys can bring added benefits: Stainless Steel: Strong. Has some corrosion to fasteners of carbon steel. Galvanized Steel: Strong. Shorter resistance to salt corrosion. Has setback requirements from the water. Zinc-Alum Coated Steel (commonly known as Galvalume): Strong. Has a higher resistance to corrosion than galvanized.
Once a metal type is chosen, next on the list of considerations is the coating/finish. According to Lord, “It is important to utilize a coated metal when on the coast. Bare metal is much more prone to oxidation, with nothing stopping the salt spray from interacting with it. A Polyvinylidene Difluoride (PVDF) coating is recommended to help keep the substrate metal free from oxidation. A two-coat coil-applied PVDF system will help resist the harsh coastal environment.” Another option is stone-coated steel, which can provide prolonged resistance. Many coil coating companies make systems specifically designed to resist the issues that commonly plague coastal roofs. Sherwin-Williams Coil Coatings offers Flurothane Coastal, “a two-coat system that uses an innovative thick-film primer to thrive in the most severe coastal environments.” This premium Copper: Though highly corrosion-resistant, copper fluoropolymer 70 percent PVDF system was created does not have the strength of steel. Warranties to deliver long-lasting protection for industrial, comand wind performance may be lower than other mercial or architectural projects within 1,500 feet of materials. Patina can stain areas of runoff. Has a the coastline. The system has been field-proven and high cost and is heavier than other metals.
FLORIDA ROOFING | October 2021