Pressure Washing Dryvit/Stucco
The challenges for Dryvit (Stucco) is that too much pressure or hot water can severely damage the siding. On this house we used a strong mix of around 8.5% sodium hypochlorite, an alkalinity booster and, a thickening additive so the solution will stay on the vertical surfaces long enough to be effective. Dwell time is critical in cleaning Dryvit. Then we regulated the rinse pressure down to around 600 psi and rinsed all surfaces down with a tip angle of 45°.
On this house we used a cold water, 4 gallons per minute application of 0.6% sodium hypochlorite and a blend of surfactants and water softening agents to make the rinsing easier and eliminate the harsh side affects of chlorine on glass and painted surfaces. After the proper dwell time we rinsed with a 1400 psi cold water rinse. We use cold water on vinyl siding because hot water can warp and twist the siding.