Roof Cleaning Dilemma

I’m in the process of cleaning g this roof and have some stubborn stains. I’ve treated it with 6% three times and it’s not even turning a lighter color. My first thought was that it’s sap but there are no trees near enough to cause this pattern. I scraped some up with my finger nail and it is not sticky. It’s mushy. The roof was black as seen in the first picture. If you look closely you can see the darker areas are the ones that will not come off. The second picture is a separate area of the roof that came out perfect today with the same mix. So I know it’s not my mix. Any suggestions? It looked better dirty tbh and that’s not good business. I’ve clean a lot of roofs and never ran into this.

image sch

It almost looks like the asphalt from the shingles but hard to tell from a picture.

Was it the exact same stuff that you were able to clean off of the other sections or did the other sections not have the goo?

Other sections did not have this goo. It almost looks like soot or fall out.

You wouldn’t think soot or fallout would be thick enough to form a goo or where you could actually move it with your fingernail. I’m just kind of thinking out loud. That’s a tough one.

It almost looks like someone was walking around on the roof when it was really hot. Does he have teenagers? Looks like they were up there playing playing tag or something.

It Looks like a defective shingle. I have ran into this a few times.

The grit on the shingle is gone it needs to be replaced. This is why I work with a roofer.

i understand that it looks like that in the pics but that’s not the case. I can scrap it with my finger nail and expose the granules underneath. I also used the m5ds to rinse it in one spot and it removed a good bit of whatever this is to expose the granule. It almost looks like some type of fallout or soot. I just used straight SH and it didn’t budge.

Defective how? The granules are there just underneath this stuff.

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It looks like the glue strip melted and ran down still needs to be replaced. Do you work with a roofer

That is not granules underneath the black. Its just missing the color granules. He should call the company who installed them and get the manufactures name and then call them for a warranty replacement. Its a lot of paper work but he should have no problem getting them to replace them.


Don’t charge for roof, explain to homeowner what your opinion is …I think the glue strip or adhesive melted and ran down is the best explanation.

Or even call a roofing company and have someone come out to inspect it and get their opinion.

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Break out the surface cleaner. Be sure to take pics for us, lol.


Lol. Here is a better picture.

Thanks everyone for the suggestions. Upon looking closer to the surrounds houses, sheds, car covers and dormers it seems to be an environmental factor specific to the area. Probably some refinery or chemical plant near by. Beat me but the stuff is all over. It’s strange how it clumps together like this. Trusty curious. I explained it to the customer and fortunately he’s very understanding. Gave him a 40% discount. I’m over it. Been on a 3hr job all day. It’s hot as hell here today on top that black roof with a head cold. Need theraflu and rest.


Not a bad idea. I’m not familiar with the texture of the glue strip but this stuff if not tacky. It’s mushy. Totally unexpected to run into this today. Supposed to be an early day. I talked to the customer. He’s understanding. If I get any call backs I’ll get a roofer to come inspect it.

If I remove the black substance(I did so in a small area with a m5ds) it reveals grey granules.

No I don’t. Never even crossed my mind.

Then its not granule loss and it may be some other substance. Let us know how it works out in the end.


I explained it to the customer. Took off 40%. Collected payment. Luckily he was understanding. I asked him to keep me posted if he finds out any further info on the substance as I would like to identify it prior next time(hopefully no next time). I’d be hesitant to clean any roofs in this are as it’s on the neighbors homes with older roofs. It’s just a bit blacker then normal algae. You can identify it in the before pictures. I plan follow up with him in a few weeks.