Fill a garden sprayer with equal parts household bleach and water. Pump the garden sprayer as instructed in the user manual to prepare it for spraying.
Cover plants below the roof and surrounding the house with drop cloths to protect them from the bleach application.
Remove any loose moss on the roof with a push broom.
Soak the shingles growing moss on your roof with the bleach in the garden sprayer.
Wait 15 to 25 minutes for the bleach to actively break apart the moss and any mold/mildew that is also on the roof.
Thoroughly scrub the roof with the push broom again to pull up the moss and clear away debris.
Spray down the roof using a garden hose to rinse the bleach away.