How to Clean Moss Off a Roof

Moss tends to grow in environments that are wet at least part of the time. Cracks and grooves between shingles where water tends to linger make the perfect growing environment for this tenacious, rootless plant. Removing the moss itself is a relatively simple mechanical process. Preventing its regrowth, which should be considered part of the cleaning process, is best accomplished with a bleach rinse once all visible moss has been removed.

Things You'll Need

• Duct tape
• Standard bristle scrub brush
• Long pole
• Garden hose with spray bottle attachment
• Bleach

Instructions

1. Duct tape a standard bristle scrub brush to the end of a long pole. Use a ladder to get yourself up onto the roof. Either take the long pole with the bristle brush mounted on it up the ladder with you or have someone hand it up to you.

2. Place the bristles of the brush against the highest shingles on the roof that show signs of moss growth. Use the pole to guide the brush downward, applying gentle pressure against the roof. This should be enough to scrape the moss off since they have no real root system. Continue scrubbing downward, working from 1 edge of a mossy patch to the next edge, and then from 1 patch to the next, until you've removed all the moss.

3. Wet all plants growing near the edge of the roof down thoroughly. This helps protect them from the bleach you're about to apply. If you can cover them with plastic sheeting, too, all the better.

4. Mix a solution of 1 part water and 1 part bleach in the spray bottle attachment for a garden hose. Don't use a pressure washer; this might damage the shingles on your roof. Direct the spray from the garden hose down the roof from the top. Make sure it flows over all the areas that had mossy growth. The spray's purpose is to kill any remaining moss growth that isn't visible to the naked eye.

5. Rinse all plants below the area of spray thoroughly with clean, bleach-free water from the hose. This helps ensure they absorb as little bleach as possible from the cleaning process.

Tips & Warnings

• If your roof is too steep to walk on safely--especially when wet--you'll need to work from a ladder at the edge of the roof instead of on the roof itself. Just place the scrub brush as high on the mossy roof as you can safely reach, and then pull down on the pole to pull the brush--and the moss it will dislodge--down toward you.

References

• Ask the Builder
• This Old House