This happens because of water and water borne pollutants but protective coatings can prevent this.
Will leaves stain my metal roof.
Our photo below shows brown stains below a metal roof chimney.
Rust or chimney soot stains red or brown rust stains around chimneys is a common roof stain.
Quite a few other issues can cause stains on a roof.
Other causes of roof discoloration.
See details at debris staining on roofs.
The solution might involve anything from waterproofing the roof to pruning the trees in your yard.
One of the easiest ways to determine if your roof is degrading is by inspecting if the paint is chalking.
Cleaning your metal roof tip 4 staining and algae lime deposits on the roof can happen over time at which point you will need to have the roof re coated.
However any damage to the coating increases the risk of rust.
These include tree shade caused moss tree shade caused lichens growth on a roof or dark stains on roof coverings caused by organic debris such as leaves and sticks that fall onto and collect on the roof surface photo at left.
Here are some clues to follow.
If metal roofing material is cut during installation it leaves an open edge of the metal exposed which wicks in moisture.
This will begin the rusting process immediately.
Spray this mixture onto the roof and agitate it with a soft bristled brush to get it clean.
Pine sap decaying leaves and even road dirt that s drifted into the air can settle on your metal roof and stain it.
Like we mentioned there are chemicals present in certain atmospheres such as acid rain and pollution particles that can cause premature degradation of a metal roofing paint system.