Cleaning Lichens from Shingles (An Experiment)

Posted by in Buying/Maintaining a Home, Roof, Shingles | October 05, 2015

While performing my annual pre-winter roof maintenance this fall I again noticed the moderate growth of lichens on parts of my roof.  The lichen growth is in areas that are heavily shaded (Figures L-1).

I thought that this might be an occasion to clean them off and give a report of my findings.

Figure L-1  Lichens on my roof.

Figure L-1 Lichens on my roof.

I thought it would be relatively easy and got a broom out to wisk them away, but to no avail.  I then got a stiff brush that I thought would remove the lichens, but not remove the granules.  Again I met with failure.  I then brought out an even stiffer brush and applied a little elbow grease.  By then I thought I could hear those darn lichens laughing as they remained in place.

I was now desperate and a little miffed at those little buggers. I went and got THE STEEL WIRE BRUSH that I had been using for an on-going painting project.  Surely, they can’t resist the power of a STEEL WIRE BRUSH!

I was still hesitant at using the STEEL WIRE BRUSH, but I had no other choice: I was NOT going to bring out the power washer – I’ve seen what a power washer can do to a wood deck and a concrete driveway, but those are another story.

I began to brush lightly and began to seen some progress in removing the lichens.  I also noticed that the granules were still holding fast, so, I pushed down a little harder.  Soon the lichens were disappearing before my eyes (Figure L-2).

Figure L-2 Brush lichens with a wire brush.

Figure L-2 Brush lichens with a wire brush.

I stopped on occasion to assess the granule loss, but I could not see any significant wear.  Soon those dreaded lichens were gone (Figure L-3).

Figure L-3 Shingles cleared of lichen growth.

Figure L-3 Shingles cleared of lichen growth.

Now, my colleagues tell me that I should warn you, “DON’T TRY THIS AT HOME! THIS UNDERTAKING WAS PERFORMED BY AN EXPERT AND IMITATING THESE ACTIONS COULD CAUSE DAMAGE TO YOUR ROOF!”  And they would be right.  I still can’t belief that it worked so well.

As a follow-up I plan to regularly examine the area where I removed the lichens to see how long it takes for them to return and to see how well the shingles hold up and report back to you.  So stay tuned.