No. Power-washing will only worsen the mold problem. The pressure of the power washer actually pushes the mold further down into the pores of the material. We DO NOT recommend power washing the decking while mold or mildew is present. If a pressure washer has been used, we recommend at least two applications of cleaner to ensure that the roots of the mold are thoroughly neutralized. A pressure washer can also, if used improperly, damage the deck surface. We recommend exercising extreme caution when using a pressure washer for deck cleaning. Remember to keep the tip at least 12 inches from the deck surface to prevent damage.