How to Remove Discoloration From Reconditioned Roof Tiles

Set a ladder against the side of the building towards the end of the structure. Enlist the aid of an assistant to hold the ladder in place for you as you climb to ensure that it doesn’t tip over.

Climb the ladder to the roof. Carefully make your way to the half of the roof furthest from the ladder location. Spread the oxygenated bleach over the roof tiles on that half of the roof, using a mop to spread the liquid generously, and working your way back towards the ladder. Cover only the far half of the roof with the bleach. Climb down from the roof and give the bleach at least 2 days to kill the moss or mold. The material will grow brown after dying, indicating the correct time for removal.

Return to the roof with the pressure washer. Set the washer on low and hold the tip of the wand 6 inches from the surface of the tile. Start the spray, and then test the water on the tile, spraying the tile for 20 seconds to check for etching. If there’s any etching of the tile surface, then switch to a lower pressure washer; if not, clean each tile with the dead moss or mold using the washer. Work your way back towards the ladder cleaning the half of the roof that you applied the bleach to. Climb back down from the roof after completion and wait about 6 hours for the roof to dry.

Switch the ladder over to the other end of the roof. Climb the ladder and repeat the cleaning process from the beginning with the other roof half. The bleach will have returned the tiles to their pre-discoloration state.