Lichen on Roof
Lichen on a roof is the hardest to deal with on a roof. It is just plain tenacious the way it digs in and clings to a roof. Scientifically the way they cling to a roof or a rock is by there anchoring hyphae called rhizines. There is something about how they work that tends to be the worst ting that grows on a roof for pulling off roof grit. When you observe roofs with lichen on them there is almost always round places already on the roof where Lichen had grown, died and pulled of the grit. I suspect these anchor structures (rhizines) just work there way around the grit hold moisture and loosen the grit from the asphalt shingles.
The Problem With Lichen on a Roof
These lichen are built to hang on tight to what ever they can get established on. Roofs, rocks, pavement, and trees are all places these greenish blue round lichen can be seen growing. To see for your self find one and try and get it off what ever it is growing on. Some thick mature lichens will come off others will just plain not budge. The same is true on a roof to be cleaned. I have found no good way to get all of them off with out damaging the roof it's self. On a roof that is walk able I have found that a light scuff of the foot will break down the surface of some of them and this helps get the cleaner application get down to the roof surface. To try and get it off with a stiff brush just does not get into the hard surface to break it up. Since the lichen is so noticeable if it can be removed righ away I do, if for no other reason it makes the initial cleaning just look way better. Instead of just waiting fro the cleaner to kill the lichen.
The Cleaner Kills The Lichen
What lichen can not be mechanically cleaned off the roof is soaked with the cleaner and it is initially turned to a white color. So the color change is proof the lichen is dead and will fall off. These lichens produce food the same way plants do they create there food by photosynthesis using sunlight energy. When the chlorophyll is destroyed the lichen dies. The remaining spots on the roof are either brown, white or reddish in color. Then over time the dead lichen breaks down and falls off. Wit steep roof this is the sole way of dealing with the lichen since getting any effective force to bear on the lichen just does not work so the result is it takes longer to see the ultimate finished product.
Time and weather breaks down the lichen so that it disapears over time. The outer coating is hard and tough so if other approaches like power washing is used on the roof substantial amounts of grit are very likely to be blasted off the roof. This is due to the fact that the water impact area can not be exactly matched to the size of the lichen and just hit the lichen. The resulting effect can be worse than the starting point. The roof grit is there to protect the rest of the roofing system from damage.
If you have lichen on your roof the blueish green blobs and or black spots created by lichen for a free quote on getting the lichen killed and off your roof so the roof will last longer and look better call 203-906-6079 or fill in the request for quote form