Moss on roof of Pleasanton, CA roofing client.

Is Moss on the Roof a Problem?

We’ve all seen those cute, picturesque paintings of cottages with smoke billowing out of the chimney, flowers blooming, and quaint rooftops dabbled with moss. As professional roofers, our eyes focus on the moss (sorry, but we don’t have time to stop and smell the roses). To the inexperienced, moss growing on a rooftop might seem like a nice idea. It adds to the ambiance, right? We’re here to tell you just how wrong that is. Is moss on a roof a problem? You bet it is. If you notice moss on your shingles, don’t ignore it (unless you want to deal with any of the problems below).

Moss displaces shingles

Rooftop moss doesn’t just sprout out of nowhere – it has to attach itself somehow via roots (also called rhizomes). These rhizomes can displace singles as the root structure begins to develop and grow, leading to missing, loose, or cracked shingles. All in all, not a good start in the moss vs. roof game.

Moss introduces moisture

Moss thrives in a damp environment. This means that, if moss is thriving on your roof, then your roof is moist and subsequently vulnerable to rot and other issues that lessen the structural integrity of the roof.

Moss causes mold growth

There’s nothing more troublesome than having a rooftop infested with mold. Unfortunately, moss is often accompanied by mold, which can quickly spread to your walls and other areas of your home. Mold is often invisible, going unseen and unsmelled for months before you realize there is an issue.

The issues outlined above are just the start of the problems that a mossy rooftop entails. What if you have to climb up onto the roof to patch a leak? Mossy rooves are wet and slippery, putting you or your roofers at a greater risk for falls and injuries. If you know that your rooftop is prone to moss growth, then you should have a professional roofer inspect and remove moss as needed. Perform frequent visual inspections on your own to determine how frequently to remove the moss from your roof.

What Can I Do About Moss on My Roof?

Recognizing that you have a moss problem is the first step – treating it is the second. Here are a few ways to remove moss from your roof.

Remove with water

Honestly, it doesn’t hurt to try the simplest method first: a garden hose, some water, and a good scrubbing. Hit the moss with a bit of water and gently scrape away the moss from the surface of your shingles. Be careful not to fall while you’re up there, and be on the lookout for any mushy spots in the roof. These will likely need to be reinforced or patched to prevent leaks.

Bleach it

This one is a bit trickier. Moss CAN be bleached away, but bleach will also damage and discolor your rooftop. You also need to protect your skin from the corrosive effects of bleach, so wear gloves, goggles, and a face mask. A little bit of gentle scraping might also be required after the bleach treatment.

Other TreatmentsRoof moss on Pleasanton roof, cleaned by Element Roofing.

There’s a magical thing called moss control powder, which is made up of mainly zinc sulfate. Unlike bleach, your roof wont’ be damaged by moss control powder. You do need to exercise caution if you live near water, and also want to be careful not to get the powder near other plants or live animals.

Roof Moss Prevention

If the above sounds like too much of a hassle (which, honestly, it likely does), then know that the most effective method is to prevent the problem of moss on your roof in the first place. Keep your trees well-trimmed to lessen the debris that falls onto your rooftop. Leaves and other foliage that collect in your gutters and on the roof itself will promote moss growth and moisture retention. Clean out your gutters on a regular basis. Also consider purchasing zinc strips and having them permanently mounted to your roof as a way to fight off future moss growth.

Do you have a roof moss problem? Tell us your tricks for treatment in the comments below!