How To Remove Moss From Your Garage Roof

There are a number of factors that may contribute to moss growth on a garage roof. If the roof is old and the shingles are beginning to decay, the moss has more space to develop its shallow roots in the spaces between the worn shingles. A tree overhanging the rooftop keeps moisture levels high and provides shade, which moss needs to thrive. The best cure for a moss-covered roof is often to replace the roof entirely. In the meantime, however, you can follow these steps to remove a substantial amount of the moss and improve your roof's appearance.

Step #1: Moisten the roof.

The moss will be easier to remove if it is moist. Unless you have had rain recently and your roof is already moist, use a garden hose to thoroughly wet down your roof. You may need to climb up on a ladder to ensure you wet down every part of the roof evenly.

Step #2: "Scrub" the moss away.

After giving the water a few minutes to soak in, use a long-handled broom or brush to brush away the moss. Keep in mind that although moss does only have short roots, it is attached to the roof – you'll have to use considerable force to dislodge it from its home. Start near the top of the roof and work your way downward. Periodically, sweep the dislodged moss off of the roof so you can see what areas still need to be scrubbed.

Step #3: Spray the roof with a moss-control spray.

There are several different chemicals that can be sprayed on roofs to help prevent future moss growth. One of these is potassium salts of fatty acids, which you can purchase in hose attachments and spray on your roof. Potassium salts of fatty acids won't harm other plants surrounding your garage, but it should not be used in areas near streams or ponds, since it can harm invertebrate animals.

Another active ingredient found in some moss control sprays is zinc sulfate. This product is also toxic to invertebrates and may harm surrounding shrubbery.

Step #4: Trim shade trees overhanging the roof.

Addressing the conditions that contributed to mold growth in the first place will help keep the mold from reappearing. If there are trees that shade your garage roof, trimming them so that the roof receives more sun will help keep moss at bay. This is particularly important if you choose to skip using a moss-control spray for environmental reasons.

Sometimes moss never returns after being removed from a roof, and other times it takes over again within months. Keep an eye on your roof after you follow these steps, and if your roof begins to look mossy again, consider calling a professional roofing company to help you address the problem, either by replacing the shingles or by using a stronger moss-control spray.