Metal Roofs are common in east Tennessee. People normally choose them because there is a misconception that they do not rust or get fungus. This is not true. Fungus definitely can eat metal roofs, so maintaining them is necessary. It is a tricky and dangerous task for a homeowner to wash their metal roof.
Galvanized Metal Roof
A galvanized roof is a metal roof with a shiny surface. It is steel with a zinc outer layer. The zinc provides a protective layer against corrosion. A home owner can maintain it through washing and make it last for 20 years. When moss or gloeocapsa magma grow on it, this can open up the zinc and expose the steel to water. Water is metal’s cryptonite and rust is more likely to form. Also, fungus will take away the paint color, leaving ugly dark patches.
The best way to clean is with sodium hypochlorite. If it is an overcast, cold day, pre-wetting may not be necessary, but if it there is sunlight, then spraying with water first gives it an even cleaning. This lowers the temperature of the roof and makes it safer to apply the chemical. If it is a big roof, the tech should do small sections at a time so that it does not dry out. A surfactant aids the water and bleach mix to stick on the roof, otherwise it will run down too quickly. It should not dwell more than twenty minutes before the rinse. If the bacteria and mold do not budge, apply more mix. The last step is to rinse it off with water.
Galvalume Metal Roof
The next type of metal roof is galvalume. This has a tin look like the bottom of a Coke can. It also has an unpainted look, although there are coated and uncoated types. Galvalume has a combination of zinc, silicon, and aluminum, is more resistant to rust but not as scratch resistant. Concrete and mortar deteriorate this type of roof since they are alkaline but galvalume reflects heat better than galvanized roofs. Since sodium hypochlorite that kills mold is alkaline, great care should taken with galvalume roofs.
An ideal day to clean this type of metal roof is on an overcast day. Use very little sodium hypochlorite and spray the roof with water first. After application, it should not stay on the roof too long. If there is a lot of mold, some scrub and apply more of the small amount of sodium hypochlorite with rinsing in between.
Don’t Pressure Wash!
Never pressure wash a metal roof. It can score it and damage the paint and coating.
Safety
Avoid standing on a metal roof when it is wet, even if you have fall protection. You can slip even on a low pitch roof when stepping on wet leaves or a wet surface. There is no grip like on a shingle roof. Special shoes with magnets are available to safely walk on steel roofs like Steel Walker 2 boots, but not all metal roofs are made out of steel. One should avoid walking on a wet metal roof even with these special boots on.
How Often Should I Wash My Metal Roof?
If there are no trees, wash the roof once every three years to keep it in good condition. All companies that sell roofs promise a set it a forget it marketing speech, but everything needs to be cleaned on a cyclical basis. If someone lives under the trees in a lot of shade, then they should wash their metal roof more often. The price of washing a roof far outweighs the price of replacing a roof.
A good way to prevent yourself making costly mistakes is to hire a professional. We can give you a free estimate to clean your roof. Contact us here.
