ISSUE
Unfortunately, roof surfaces can sometimes be subject to overspray or splatters when other improvement projects are undertaken on the building. This might be paint or stucco coatings or perhaps other materials. When this occurs, it damages the aesthetics of the roof system and is cause for concern.
ANALYSIS
Looking fully at these situations is important. In some cases, it really needs to be closely evaluated whether a significant problem exists or if it is something that really is not that noticeable which might become even less noticeable in the future as weather and natural dirt accumulation occur. Additionally, some consideration should be given as to whether the roof system in the affected area can be easily replaced or, in the case of some metal systems, capped with new panels. However, if desired, there are steps which can be taken to clean the metal.
CONCLUSION
Cleaning the overspray requires a two-fold approach. First, you must find out what sort of material will act as a solvent on the offending paint or other stain. This can usually be done by consultation with the manufacturer of that material. Certainly, a first step should always be to scrub with a solution of water, detergent such as Tide, and perhaps trisodium phosphate (TSP) such as Soilax. However, in most cases, more substantial action will be required. With some materials, power washing may do the trick. With others, you may need to investigate a product such as a light sulphuric acid solution or a typical mineral spirits based solvent. Such materials should always be tested on a small inconspicuous roof area before embarking on the entire affected area. If possible, consult with the roofing manufacturer or the manufacturer of any coatings on the roof system before proceeding. All such materials should be rinsed carefully from the roof with clear water after cleaning and before they have dried. Various types of coatings are used on metal roofing. The widely recognized quality leader amongst coatings is Kynar / Hylar finishes, one benefit of which is their ability to favorably resist strong cleaning with some of the chemicals mentioned herein. Always take proper safety precautions when carrying out this work on the roof surface.
