When Is It Time To Clean My Roof?

Updated: Mar 8

There have been huge technological developments in roofing technology. Some of the leaders in asphalt shingles offer roofs that are expected to last 20-30 years. This is especially helpful when you consider that the national average cost to replace a roof is $8,194 and upwards of $13,800 in the greater Seattle area. But while roof manufacturers are increasing life expectancy and developing new technologies to help protect us from the elements, many homeowners are unaware that their roof is only designed to last as long if it is well maintained.


Let's take a car for example. Cars are designed to last for hundreds of thousands of miles but they require regular maintenance in order to reach their full life expectancy. The same is true with roofs. Left uncared for, you will dramatically cut down your roof efficiency to protect the rest of the home.


Cleaning Your Roof

There are a number of solutions that you can purchase from your local hardware store to help maintain a roof and prevent growth. One of the most popular, Moss B Ware, comes in a 3lbs can that you shake to distribute zinc sulfate monohydrate onto your roof. This is a low-cost option but is a partial solution. Zinc sulfate monohydrate and other zinc products like the strips you install on your roof are mainly used to prevent growth but not kill existing. The zinc changes the PH balance of the rainfall that hits the roof creating a poor environment for the moss to grow. We would only recommend this as a preventative measure and not a cleaning one.


Some contractors offer services that get on the roof and use a combination of brushes to knock the growth off. This is absolutely horrible for the roof. Your roof is made of granules that are designed to shed water, protect the home from ultraviolet (UV) light, and offer fire resistance. When a roof is brushed off, valuable granules are lost in the process, effectively accelerating the age of your roof exponentially. And gaps in the roof are exposed when larger clusters that have deeper roots are yanked out. Brooms, wire brushes, and high-pressure water can take 5-10 years off your roof's life expectancy or worse, cause leaks today.


So what do you do if you are already seeing discoloration or growth? Simple. Hire a professional. Experienced roofing professionals use a treatment comprised of sodium hypochlorite (the active ingredient in bleach) and a surfactant (a fancy word for soap). Mixed in the appropriate ratios this treatment is applied through a process called soft washing and will coat your entire roof using low-pressure water. Sodium hypochlorite kills all organic matter on the roof, destroys the environment for growth to reoccur, and restores the color of your roof. Depending on how long the growth has been allowed to develop, the restoration results can take time. If your roof is mainly comprised of dark streaks, you should see results within hours or days. If green growth has set in, results can take 1-6 months. It's important not to rush this process. Soft washing is a long-term solution to a long-term problem and you have to give it time to minimize damage to your roof.


Dark Spots

A sign that you need your roof serviced is observing its color. The roof's color should be even and consistent across the entire surface. If you are seeing that it is getting darker in areas or has even turned black, then it's time for service. These are deposits of growth creating an organic base layer that further growth can thrive on. While you are not in immediate danger of long-term damage, you should consider servicing your roof within the next 12-18 months.

Green Spots In Between Shingles

Those green spots are growth. Moss and lichen love to get in between the shingles on your roof. They separate the shingles and weaken your roof's ability to keep water out of the interior of the home. Moss thrives in wet and damp environments that do not get direct sunlight. Because we are in the northern hemisphere of the world, you'll notice that growth tends to happen on the northside of the home first. If you are seeing green growth in your home, there is a good chance that it has not been serviced for 3-5 years and needs attention quickly. We recommend having your roof cleaned within 1-6 months.


Full-On Growth

This is a worst-case scenario. You have to know that if you are seeing full-on growth on your roof, it is being compromised. Water is not leaving your roof fast enough, there is an enormous amount of weight added, your roof's ability to fight off UV light has dropped and its fire resistance is endangered. We recommend having a service professional come out and treat your roof as soon as possible.

Thank you for taking the time to read this article. If you need professional roof cleaning or any other soft washing and pressure washing services, call Power Clean Pressure Wash at (253) 655-7474 to get a free and fast quote over the phone.

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