Home maintenance question - roofing

[BobT]

My roof is relatively new (3 years old). I've begun to notice that on the north side where the sun doesn't make good contact there appears to be some kind of moss or lichen growth. My old roof was the same way so I don't believe it has much to do with the type of shingles. This roof is 40-year, 90mph rated, architectural shingles.

Does anyone know if this is a concern and if so, any ideas of treatment to rid the roof of the growth without damaging the roof?

Thanks,

Bob

[gulllakeguy]

You can apply a galvanized/zinc metal strip that slides underneath the top coarse of shingles. It runs all the way across the roof and a couple inches of it shows. Most new shingles have a moss/lichen inhibitor built right into the shingle but this is a fairly new thing.

[BobT]

What does the metal strip do way up there?

[Tom7227]

The zinc lets out some chemical or mineral that stops the lichen and moss from growing. You should take steps to remove what's up there now, especially if it is the heavy moss type. I have heard there are products that you can use for this. I wonder if you could just use a mild bleach and water solution to knock it off.

[sparcebag]

I believe zinc is a magnetic field,short distance help.Copper is the way to go a copper wire run just down from the ridge the legnth of the moss Copper charges the ions and inhibits the growth as water flows over it.And yes the growth will shorten the life span of the shingles.

[Roofer]

Yes. the strips will keep it from growing, but it won't kill what is there. I don't know of a chemical that is safe. That doesn'y mean there isn't something out there though.

This is where the Landmarks are better than the rest. They have roughly 20% more copper in them than the others.

In the past this was a special order for AR (algae resistant), especially on 40 years. Now it is standard on the whole lineup. GAF has it also standard, but it's not as much copper in them.

If it was me, I would try to clean them by hand in order to try to lose less granules, then add the zinc strips according to specs.