how to remove moss from a roof

How to Remove Moss from a Roof

Even though Colorado is mostly an arid state, moss does grow wherever it can. Typically, shady conditions combined with sufficient moisture will often provide moss with the opportunity to grow without constraints.

This is great for natural areas where moss is incredibly important ecologically. However, when it comes to protecting your home or commercial building from water leaks and other elemental damage, moss can become a real problem. 

On roofs throughout Colorado, moss can often be found growing directly onto asphalt shingles, flashing, and even on brick or mortar. Wherever there is enough moisture, shade, and time, moss will find a way to prosper! 

Why a Mossy Roof Is a Problem

Now, you might be thinking, “What’s wrong with just letting it grow?”. This is a question which makes perfect sense to ask. The reason you don’t want moss to get out of hand on your roof is because it will quite literally shorten the lifespan of the roofing materials that protect the rest of the building. 

It might be helpful to think of moss as acting like a sponge when it rains or snows. After all, most Colorado mosses are fairly dense, and they retain water for quite a while even after the sun comes out from behind the rain clouds. Over time, this water retention will slowly degrade virtually any conventional, asphalt-based roofing material. 

removing moss from roof

Furthermore, wet moss is heavy. Large patches of it can place a significant weight burden on the roof, and it might not be built to withstand this additional pressure!

Now that you know the reasons why a mossy roof can be potentially destructive, let’s explore the actions you can take to safely remove moss from your roof (and even help prevent it from coming back). 

Roof Moss, Begone! 

First things first: if you’re going to attempt to remove moss from your own roof, please be sure to take safety precautions! This includes using fall protection equipment wherever possible and working with a partner. 

Once you’ve donned your safety equipment, take the following steps to remove existing moss from your roof:

  • Use a push broom or bristle brush to lightly remove old or loose moss that has accumulated on the roof. When doing this, take care not to remove too much of the gravel granules that are integrated into your asphalt shingles. Those granules play an important role in protecting your building.

    As tempting as it might be to use a pressure washer for this step, we don’t recommend it. Water pressure power can be enough to damage shingles, and the wet roof can pose a safety risk while you’re working.
  • Install a zinc strip. As a preventative measure, install a strip of zinc metal along the highest spine of each roofing section. Doing this will slightly modify the pH of the precipitation that falls on the roof, causing it to kill off many mosses, lichens, and molds found here in Colorado.

    Wear gloves while doing this, as the edges of zinc metal strips can be quite sharp. Also, take care to use roofing epoxy to seal any nails you use to affix the zinc strip to the roof.
  • Apply a bleach solution to the roof. Using a handheld pump sprayer, apply a 1:4 bleach-to-water solution evenly across the entire roof surface. Be sure to start at the lowest section of the roof first, so you’re not treading on wet roofing as you work your way up. Because bleach is an antifungal and antibacterial disinfectant, it will kill any actively growing moss it comes in contact with in just a few days.

    Take care not to use so much bleach solution that it runs down the roof and onto plants or foliage below.

And that’s it! From start to finish, cleaning moss from a typical single-family home shouldn’t take more than a few hours. Don’t forget to always, always use fall-rated safety equipment if you’re intrepid enough to do this job on your own.

If you’re not, and you’d prefer to leave it to the experts, then don’t hesitate to give us a call at A-to-Z Roofing & Exteriors. When we perform a professional roof cleaning, we’ll also conduct an inspection to determine if there are any sections of the roof that might be in need of repair. 

Our passion is keeping Colorado roofs in outstanding condition season after season. We’ve been doing it since 1993, and we’d love to earn your business. When you’re ready to schedule your moss cleaning, contact us

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