Softwashing is the safest and most effective way to clean asphalt shingles, as well as many other exterior surfaces. We use a 100% bio-degradable formula, a quiet, eco-friendly 12-volt pump system and about as much pressure as your average garden hose. Best of all softwashing is recommended by The American Roofing Manufacturers Association (ARMA). Traditionally, pressure-washing was the preferred method of exterior cleaning; but high pressure on a gentle surface sometimes does more damage than good, and is sometimes just plain ineffective. We all know what happens when we trim a weed... it grows back thicker and healthier! Pressure washing a roof may remove the surface stains, but in very little time, they come right back.... THICKER AND HEALTHIER!