What to Do About Green Moss on Your Roof
Heavy rains are doing more than filling our reservoirs and causing flooding. Some of you are seeing spongy patches of bright green moss growing on your roof shingles or tiles.
I know because you are calling us to ask whether that green stuff on your roof is harmful. Don’t panic. Moss grows almost anywhere, on any surface.
Moss is dormant in dry weather and grows like crazy in humid, wet weather.
In Oregon and Washington, it can be a cause for concern. On some roofs it grows lush and thick, making its way under the shingles. It can also damage the shingles themselves, allowing moisture in.
In our area of Northern California, real damage from moss is rare. The spring sun will burn it back to a dormant state.
If your home is located in a grove of tall redwoods, or is tucked into a hill in West Marin, take a closer look. If the surface of your roof doesn’t get much sun, in any season, you have a better environment for large a simple cleaning can remove it.
In some cases, with light areas of moss, you can use a broom to loosen it and brush it off. For stubborn moss you will need stronger measures.
Don’t’ Do This!
Whatever you do – don’t use a power washer. Power washers are great for removing that slippery moss from your patio bricks. Fast – easy, but pressure washing does more harm than good.
The force of the water can damage shingles, shakes or disturb the bond between tiles. Moisture can actually be forced under the shingles.
What Really Works to Remove Moss?
In some cases, with light areas of moss, you can use a broom to gently loosen it and brush it off. For stubborn moss you will need stronger measures.
Moss likes moisture, shade and grows on just about anything. It will even grow on roofs that have a zinc strip if the strip has been on there for a few years.
What about Chemical Options?
So, if you aren’t into cutting down your trees or moving the hillside that blocks your home from getting sun, chemical measures are an option. You could make a solution of 25% bleach and 75% water to spray on the affected areas, wait a short time and rinse it off with more water.
Try it on a single shingle to make sure it doesn’t strip the color away.
Another less toxic solution is made by making a solution that is 15% vinegar and 85% water. Spray on and rinse.
There are a number of commercial products on the market, designed to kill and/or prevent moss. Remember, whatever you use, the solutions will eventually come off the roof and onto the ground and plants below.
Before you try anything, keep in mind, waiting for the spring sunshine might be your best option. If curb appeal is a concern, or you are still worried and need a second opinion, one of our team will be happy to provide you advice. Contact us today.