White spots

on wet roof covering??

Any hail your area lately?

Can’t tell from your pics - was it lichen?


The white is Bird poo and the green is algae .
The Galvanized Vent is adding a small amount of Zink slowing down the growth behind it .
They have replaced one half of the roof

That’s what it looks like. We’ve had hail in the “area” (50 mi radius) over the last few months.

Notice replaced front side, maybe thought rear wasn’t damaged enough. Owner no longer present.

My first though was hail, but, there seems to be a pattern, or consistency to the spots. It is most likely a blemish or defect from the factory. Were they purchased at “Roofing Liquidators”?

Definitely a consistency. No indentations I could notice. A little much for bird poop. Don’t believe it was algae, again it was wet from light snow/rain. May have been algae that was “washed” off.

Did you taste it? Bird poop tastes like…bird poop:twisted::twisted::twisted::twisted::twisted::twisted::twisted:

My bird poop taster didn’t show-up. :mrgreen:

Low flying Geese:D:D

I was in the roofing business many years when younger. We have a lot of hail damage in our part of the country. Without being on site to look closer, I would go with hail. If the hail is large enough, it will fracture the fabric on the back side of the shingle. Sometimes home owners replace part of the roof and pocket the rest.

Here are similar spots on a different color roof. Insurance adjuster and roofing company came out, verified hail damage and replaced the roof.

The impact can ‘clean the granular’ so to speak and change the color at point of impact. After a period of time, the color will began to fall in line with the remaining part of the shingle.

All joking aside me living in the smack dab middle of the hail belt just from the altitude of your pic’s I would have to say hail also

Yep Hail, they only replaced the worst side, or the they saved have the claim lol

Thanks everyone

Hail comes in all different densities. Soft hail leaves spatter marks that remove dust, oxidation, dirt and microbial growth. Looks a lot like that.

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soft hail = graupel

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I work primarily in the Insurance/Roofing Industry and this is known as Hail Scrubbing. Algae tends to grow on some roofs for a portion of the year, depending on the season and climate. When hail impacts the shingles that have algae present, it causes whats known as a scrubbing effect leaves this discoloration on the shingle. These blemishes are usually present fro the remainder of the roofs life, even once the algae is gone. In my world, this is considered damage to the shingle and has often fractured the matting behind the impact, even if there is no apparent granule loss. We contract with a large Public Adjusting firm and have had many roofs replaced with similar Scrubbing. Hope this helps!

Maybe someone threw rock salt on the roof to melt ice and it killed the mold and left spots. Also if you throw powdered laundry detergent on the roof and just let the rain wash it off it will clean the mold off the roof it can leave spots, if there is a lack of rain or not enough detergent. or maybe hail like the others said?

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