Have you noticed green growth on your roof, probably occurring mostly in the spaces between your shingles? What you're seeing is probably moss growth. Moss-covered roofs are often depicted in fiction as charming and attractive. Moss can resemble soft green carpeting, and from a distance, it really can look like a decorative addition to a building. However, when the moss is growing on the roof over your head, it's less of an accessory and more of a nuisance. Take a look at the facts about how moss can damage your roof, and find out what you can do to stop it.
What's Wrong With Moss?
It's easy to view moss as a pretty benign growth, and that's usually the case when the moss is growing anywhere other than your roof. However, moss is highly absorbent – there's a reason why it's used in gardening for mulch – and that means that when it rains, the moss on your roof is grabbing and holding water that should be running into your gutters and away from your roof. You can wind up with water damage in the spots where the moist moss is growing – and that can lead to mold growth underneath the moss, on your ceiling. Mold is a lot less attractive and benign than moss.
What's more, as the moss grows and expands, it can actually begin to push your shingles up and out, loosening them. If the moss growth is allowed to spread unchecked, your roof will eventually need repairs to replace shingles that have been damaged or fallen off entirely.
How to Get Rid of The Moss
Fortunately, moss isn't all that difficult to get rid of. Avoid scrubbing at it or using a high-pressure hose to get rid of it – harsh scrubbers and high pressure can easily damage your shingles as well. Instead, mix equal parts bleach and water and spray it into the areas where the moss is growing. This changes the pH balance of your roof to a more alkaline pH, which is deadly to the moss.
How To Keep the Moss From Coming Back
Once you've gotten rid of the moss, the next order of business is to prevent it from growing back. Keeping your roof dry is an important start – moss requires moist conditions to grow, and if your roof is shedding water effectively, it will have less of a chance to grow back. Cut back any branches that are overhanging your roof. When it rains, those branches will drip water and wet leaves onto your roof, keeping it from drying off as quickly as it might otherwise. Also, check to make sure that your gutters are clean and clog-free. Standing water can encourage moss growth. If water can flow through your gutters freely, there's less chance of having standing water on and around your roof.
Once that's done, you may want to consider installing zinc strips on your roof. These are flat, metal pieces of flashing that you will install in a straight line across the top of the roof, partially overlapped by shingles. Zinc inhibits moss growth. When you install zinc strips at the peak of your roof, the rain drops will hit the strips and carry zinc particles from the strips as they roll down your roof, covering the roof in zinc and preventing moss spores from growing. This is an effective way to prevent any further growth on your roof. Installing the strips is easy enough if you're up for a DIY project, but remember that working on top of a roof can be dangerous – if you have any doubts about your ability to work safely on the roof, hire a professional to do the job.
Moss isn't good for your roof, but if you take care of it in a timely manner and prevent it from coming back, you may be able to avoid expensive roof repairs.