Roofs are not usually green and growing. If yours appears to be covered in moss or lichen you may have a bigger problem than you realize. Here is what a lot of lichen on the roof means, and how to remove it.
Moss and Lichen Like Wet, Rotting Things
Moss and lichen like to grow where there is a lot of moisture and a lot of rotting organic debris. If a lot of leaves fall on your roof in autumn and do not come down through wind, rain, snow, and ice, they will sit there and rot. Additional moisture supplied in the spring creates openings in your shingles for the first sporophytes from moss and the spores from the fungi responsible for lichen to settle in.
Additional Damage to Your Roof
The problem with lichen and moss spreading across your roof is that they will eventually move down through the roof and into the attic or ceilings of your home. Here, with openings they have made in the roof and shingles, they are watered continuously by weather, and the heat inside your home gives rise to the perfect environment for these things to grow and destroy. Moss and lichen that are not removed can utterly destroy your roof in a few short years.
How to Remove These Plant Species
Your roofing contractor can use a mist of herbicide to kill the moss, but the lichen need to be destroyed with a fungicide. It is not a good idea to use these two chemicals together, so the roofer may spray your roof with the herbicide first, attempt to scrape away the dead moss a few hours or days later, and then spray your roof with the fungicide. Any shingles that are badly damaged or reveal a hole from the roof to the interior will have to be removed, replaced, and repaired.
Keeping the Mold and Lichen from Returning
Prevention is the best cure for mold and lichen on your roof. Have a roofing contractor blast down any leaves and debris late in fall when the trees are finally bare. Clean out the gutters where moss and lichen can settle for the winter. If you see a fresh new green spot on your roof, ask your roofing contractor to return, check it out, and blast it again to prevent further damage. If the current damage extends inside your home, you will need a mold remediation contractor to address the problem and fix the damaged areas. Contact one as soon as you can for more info.