Asphalt Cleaning Solutions
“Because asphalt shingles are the most popular type of roofing material, there is no shortage of advice and DIY internet recipes for cleaning them. The most popular recipe includes chlorine bleach, water, and trisodium phosphate (TSP). However, there are several dangers associated with this combination, including the fact that bleach only kills the surface layer of mold and algae, opening it to regrowth. Furthermore, it poisons the vegetation underneath the roof and corrodes metal fastenings. Another common product, sodium hydroxide (lye), is safer for plants but toxic to humans and similarly corrosive.”
So what gives? First I’ve heard that SH “…only kills the surface layer of mold and algae, opening it to regrowth.” Is this an effort to drive the DIY’s to safer, more expensive proprietary products sold in big box stores?