Many people opt for a metal roof because they like the look of the clean lines and appreciate the durability and long lifespan of the material. Metal is also considered low-maintenance, but it isn't no-maintenance. Stains can occur on your roof, but they are fortunately easy to remedy if you know what to do. The following guide can help.
What causes staining on metal roofs?
There are several different causes of staining, but the most common are rust, mildew or algae, and organic stains – such as from bird droppings or pollen. Rust appears as a reddish orange stain, while mildew or algae can look green or black. Pollen stains tend to be a pale yellow in color.
Are there ways to avoid rust stains?
Rust is the result of oxidized metal – or metal that has been exposed to oxygen. Choose powder-coated metal roofing with no exposed bare metal, and make sure all screws, nails, and hardware are made of galvanized metal, which is rust-proof. Flashing and metal pipes on the roof should also be a rust-proof material. Oxidation can also occur due to an electrical current. This means you need to make sure no grounding wires are attached to the roof.
Is algae and mildew avoidable?
Yes, you can completely eradicate this problem by having a zinc strip installed beneath the ridge cap on your roof. Rain and dew will cause the zinc to leach out and down the entire roof. This isn't visible, but the resulting zinc creates an environment where mildew and algae cannot grow.
What about organic stains?
The only way to avoid bird droppings is to make sure birds don't nest on your roof. You can do this by installing scare devices or opting for a steep pitch that dissuades birds from landing. Pollen is more difficult to avoid if you live in a pollen-heavy area. You may be able to minimize it by avoiding the planting of heavy pollen producers in your yard.
How are stains removed?
Fortunately, stains can be removed once they have occurred. The following tips are specific to each stain type:
Rust: If the roof's finish is undamaged, replace the hardware, flashing, or vent pipe that has rusted and caused the stain. Remove the rust stain from the metal panel with a cleaner containing trisodium phosphate (TSP). If the roof panel has rusted, remove the rust with a wire brush and then repaint the roof with a rust-inhibiting paint.
Mildew and algae: On metal roofs, pressure washing may be all that is necessary to remove these stains. For more stubborn stains, use a mildew and algae remover and scrub the roof with a deck brush.
Bird droppings and pollen: Remove heavy droppings promptly, since they are acidic and can damage the paint on the metal. Pressure washing is usually sufficient, but you may need to scrub with a deck brush if the droppings have baked on in the hot sun. Pollen can usually be rinsed off, but you may need to scrub if sap has caused the pollen to become sticky. For more information, contact a roofing company like JD Metals.