Tips for removing lichen from roofs

Person pressure washing mossy roof safely.


Lichen doesn’t only grow in pavers, decks, and furniture, it also grows widely on roofs and it can lead to severe water damage if it is not dealt with on time.

Lichen can be removed by numerous methods with the help of vinegar, bleach, and dishwashing solution. The process includes a lot of rubbing, so you have to be prepared for that!

You do have an option to look out for professional help and it is a beneficial move to ensure that your roof is free of lichen and other impurities. But you do have a DIY option.

In this blog, we will discuss various DIY methods you could use to completely get rid of lichens from your tiles and how you can prevent the regrowth of lichen.

What are lichens?

Before getting rid of lichens, it’s important to understand why there are lichens on your roof.

Lichen is a very complicated form of life that emerges from a symbolic merger of two different organisms; a fungus and algae.

Fungus is the dominant partner, which gives lichen its thallus shape and fruiting bodies. The algae can be either green algae or blue algae which also goes by the name of cyanobacteria.

Most of the lichens have both types!

Most common types of Lichen

The most common type of lichen is formed up of Trebouxia (green algae, single-celled). This form of algae is found worldwide in alpine and arctic regions.

Lichen can grow in any sort of temperature provided. Lichen is not affected by weather conditions which is why they can grow on any roof worldwide.

How does Lichen look?

Lichen on tree bark in the forest.
Lichen on tree bark in the forest.

Lichens are a diverse and fascinating group of organisms, exhibiting a wide array of forms, sizes, and colors, making them both intriguing and sometimes challenging to identify. Here’s a more detailed look at their appearance:

  1. Variety in Forms and Structures:
    • Leafy (Foliose) Lichens: These lichens resemble small, leaf-like structures that are often lobed and layered. They are typically found adhering closely to the surfaces they grow on but are not completely flat.
    • Shrubby (Fruticose) Lichens: These are more three-dimensional and can look like miniature shrubs or tufts. They are often found growing upwards or hanging from their substrate, giving a moss-like appearance.
    • Crusty (Crustose) Lichens: These form a crust directly on the surface, almost like a painted-on appearance. They are the most common type on hard surfaces like roofs and walls and are the hardest to remove due to their close adherence.
  2. Color Variations:
    • Green and Blue-Green Shades: Often indicating the presence of chlorophyll, these colors suggest that the algae component of the lichen is actively photosynthesizing.
    • Yellows and Oranges: These bright colors are usually due to the presence of specific pigments in the lichen, which can sometimes act as a sunscreen, protecting the organism from intense sunlight.
    • Browns and Grays: These colors are more common in lichens found in shadier, moist environments. The color can also be influenced by the substrate they are growing on.
  3. Texture and Size:
    • Textures: Lichens can range from smooth and glossy to rough and scaly. Some have a powdery appearance, while others might look more fibrous.
    • Sizes: The size of lichens can vary greatly, from tiny specks only a few millimeters across to sprawling mats that can cover large areas of a roof or wall.
  4. Patterns and Growth Forms:
    • Patterns: Lichens can form intricate patterns, often in circular growths, which can be used as an identifier. These patterns sometimes resemble maps or webs.
    • Growth Forms: Some lichens grow in a dispersed manner, while others form dense, tightly-packed clusters.

By understanding these various aspects of lichen appearance, homeowners can better identify the type of lichen they are dealing with and choose the most effective removal and prevention methods. Whether it’s the leafy greens and blues of foliose lichens, the vivid oranges of crustose lichens, or the bushy, shrub-like forms of fruticose lichens, each type requires a slightly different approach for effective management.

Is Lichen harmful? Is the removal necessary?

Lichen can appear to be harmless but it is capable to cause severe damage to surfaces it grows on overtime. It can reduce the life and efficiency of your roof.

Lichen can freeze in extreme cold weather and it can cause damage to surfaces and asphalt shingles. Lichen holds the moisture against the surfaces which speeds the wear and tear of the roof. So your roof shingles might bend and wrap.

Lichen is also able to penetrate the exterior of the roof causing asphalt shingles to separate and cause a huge disaster.

Following are the methods that you could use to get rid of the Lichen on your roof;

  • White Vinegar and Dish Soap
  • Oxygen bleach
  • Water Hose
  • Metal Strip

White Vinegar and Dish Soap

Vinegar is acidic, which is why it can easily kill lichen and makes it extremely easy to scrape it off the surface.

You can start by removing organic matters from your roof such as leaves, debris, twigs, etc.

Then you have to add your vinegar (white vinegar) in a tub and add 1oz of dish solution, then you have to pour the mixture into a spray bottle and simply spray it around the edges of the lichen growth area. You need to repeat the process for several days, when the lichen will be killed then you can either scrub the dead lichen or use a pressure wash to remove it from your roof.

Using Oxygen Bleach

One of the natural ways of removing lichen is using Oxygen bleach. Oxygen bleach is commonly and widely used to remove lichen.

Oxygen bleach contains sodium percarbonate which is a key ingredient to kill the fungus. It is a more suitable option than using chlorine bleach. Oxygen bleach will not discolor the surface of the roof tiles. It is also safe to use on asphalt surfaces.

All you have to do is to pour 1 gallon of hot water into a bucket and add 8oz of oxygen bleach. You have to wait 5 minutes to allow the bleach to dissolve in the water. Then pour the solution into a bottle of spray. To prep, the roof for cleaning you have to wet it first and then spray the solution to the affected surface. After that, you are supposed to let the bleach sit for about 20 minutes and then scrub it off later using a long-handed brush before rinsing the area with a water sprayer. You can repeat the application if necessary.

Using a Water Hose

Pressure washing moss off a roof.
Pressure washing moss off a roof.

At times only pressure washers can be enough to kill the growth of the lichen. The force from the pressure washer can easily kill the lichen.

It is considered the safest method to remove the lichen as it does not involve the use of harsh chemicals.

Using metal strips

Lichen tends to avoid copper, galvanized steel, and zinc because these metals work as a natural biocide. Installing these metals strip along the ridge of your roof may prevent the lichen from growing. On a rainy day, the rain will moisture the strip and a certain amount of metal will run down on your roof making your roof inhabitable for the lichen. However, this must be known that copper and zinc are harmful to the environment. The runoff can find its way into a pond or stream causing environmental issues. So you need to look out for that.

Final words

Lichen is a pest that grows on your roof if the conditions are habitable it can cause serious issues if you fail to remove the pest on time. You can either DIY  it or seek professional help to get rid of the pest growing on your roof.

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