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Black streaks on shingled roof

bczoom

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I have these black streaks on my roof.
I've been told it's some sort of algae or something. I was told (by the same person) that a bleach/water mix sprayed on it will make it go away.

Thoughts? If the water/bleach is the resolution, what's the mix or ratio?

Thanks
 

OkeeDon

New member
Mildew. Bleach works fine. Weak solution -- try about 4:1 water first and see what happens, go stronger if necessary. I use liquid pool chlorine rather than bleach. Use a pump up sprayer (or a battery powered one if you have it), wet it good, keep it wet, you should see the mildew disappear. Rinse it with a hose; you can use a pressure washer, but use it with a very soft nozzle and very low pressure so you don't blow the granules off the shingles.
 

bczoom

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OkeeDon said:
Use a pump up sprayer (or a battery powered one if you have it), wet it good, keep it wet, you should see the mildew disappear.
Thanks Don.
I have pump sprayers.
Can you elaborate on "keep it wet"? I was thinking of just spraying it then leaving. The next rain would wash the black off. Is that wrong?
 

working woman

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It is true it is algee,mold and its uguly but leave it. Pressure washing or any washing will only shorten the life span of the shingles. the tinly little granulas on the shingles are there for a reason and one of them is to make the shingle last.

I know this is becasue I was married to a roofer for 18 years
 

bczoom

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First Lady,

OK to spray the bleach solution on it but just let the rain wash it off?
 

Melensdad

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working woman said:
I know this is becasue I was married to a roofer for 18 years


Before you killed him off and buried him the back back yard :whistle:

OK on a serious note, I totally agree with you that pressure washing an asphalt roof is a really bad thing because of the exact reason you stated, but would a hand/pump sprayer, with its very low volume and pressure present much of a problem? I would guess that the algae would cause more potential harm than a soft washing of bleach? Honestly, just a guess, I don't know.
 

OkeeDon

New member
bczoom said:
Thanks Don.
I have pump sprayers.
Can you elaborate on "keep it wet"? I was thinking of just spraying it then leaving. The next rain would wash the black off. Is that wrong?

Have you ever used X14 on mildewed tile or a convertible top or an RV awning? It's basically bleach and works the same way. When you spray it on mildew, if you keep it wet for a few moments (by respraying before it dries), you can literally see the mildew disappear. I suppose you don't have to rinse it, but I always do.

The black streaks are very common in Florida, and many, many home owners associations required the residents to clean them. Professionals who provide the cleaning service clean them the way I outlined, but then spray a proprietary solution with a residual mildewcide to prevent it from coming back as soon. Many such services provide an annual contract.

Working Woman is correct about the granules, which is why I cautioned about the pressure if you do rinse. However, spraying and hosing the roof will do no more harm to the granules than a Spring rainfall.
 

working woman

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The roofers advice was to leave it alone. Next time buy fungis resistint shingles. They are more expensvive, but well worth it.
 

bczoom

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working woman said:
The roofers advice was to leave it alone.
Oh man... (I mean woman)...
You're saying that I should just look at all that black stuff until I replace the roof? Throw me a bone. Tell me I can do the bleach thing. I really want to do something with it. My house sits down low and the roof is very visible. It looks like crap.
 

OkeeDon

New member
I'm sure the roofer was well-intentioned. But, leaving it alone is not a good idea. According to several sites I visited after a quick Google search, moss, mildew, algae and fungus can discolor your roof, feed on the organic material in your shingles and eventually destroy them. Leaving it will shorten the life of the roof. I suppose a roofer might make that recommendation? It's to his benefit.

Here are a couple of sites that discuss roof cleaning. The first is a handyman site. The second is the University of Florida Extension Service. I don't believe the University would recommend anything that would harm your roof.
 

bczoom

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Thanks Don. I'll read the links you provided.
I was just going to spray some bleach and let mom-nature take care of the cleanup.
 

DaveNay

Klaatu barada nikto
SUPER Site Supporter
bczoom said:
Thanks Don. I'll read the links you provided.
I was just going to spray some bleach and let mom-nature take care of the cleanup.

Knowing my luck, I would spray the bleach and then we would go into a 6 month drought, and the bleach would cause the mildew to become genetically modified and would eat the roof.:smileywac
 

OkeeDon

New member
bczoom said:
Thanks Don. I'll read the links you provided.
I was just going to spray some bleach and let mom-nature take care of the cleanup.
Do read them -- both recommend rinsing, and provide some good reasoning for it. They also have some valuable tips about landscaping and such.
 

BadAttitude

New member
OkeeDon said:
Mildew. Bleach works fine. Weak solution -- try about 4:1 water first and see what happens, go stronger if necessary. I use liquid pool chlorine rather than bleach. Use a pump up sprayer (or a battery powered one if you have it), wet it good, keep it wet, you should see the mildew disappear. Rinse it with a hose; you can use a pressure washer, but use it with a very soft nozzle and very low pressure so you don't blow the granules off the shingles.
Don
Does the pool chlorine really work? If so...is Pool SHOCK the same? I've been told bleach/h20 will stain dark shingles, so I've avoided using it. My north facing porch roof has this same mold/streak condition every few yrs and in the past I've just used a pwr washer with great results. But as mentioned...used it at a safe distance to avoid loss of granules. I'm now interested in spraying to see if it extends the relapse time.
 

BadAttitude

New member
working woman said:
The roofers advice was to leave it alone. Next time buy fungis resistint shingles. They are more expensvive, but well worth it.
ww
Wish I knew about those treated shingles when 1/2 my roof was blown off during a New England blizzard in 96. I had heard about them about 2 yrs ago...how long they been on the market? I DO plan to use them next time around though.

a FYI for all...copper strips attached along the peak are supposed to help control this growth. Anyone ever tried it?
 

OkeeDon

New member
BA -- check the links I provided; they provide some safe alternatives to bleach, if you're concerned that bleach will darken the shingles.

I'd be concerned about a copper strip -- doesn't copper turn green and bleed off on surrounding materials?

As mentioned in the links I provided, Florida is the worst when it comes to the black streaks (by the way, one of the sites starts off by saying that for roof purposes, mold, algae, mildew and fungus all have the same meaning), yet none of the roofers specifically mention the fungicide shingles. I suspect that all of the shingles commonly sold in Florida have some degree of fungicide (and that it doesn't really work), or that none of them do because the roofers have found that it really doesn't work. Believe me, if they thought they could get an extra dollar out of a job by selling special shingles, they'd do it -- unless they've discovered that it doesn't really work.
 

BadAttitude

New member
bczoom said:
I thought I recall the strips were zinc, not copper.
Copper is supposed to be better...or so I've been told by a few pro roofers

Ahh, that's it...zinc:tiphat:
I knew there was another one:confused: ...but this dang CRS just keeps getting worse:whistle:
 

working woman

New member
Site Supporter
No, the shingles in Fl. do not come with a certain amt. of fungicide.( I know husband had succesful bus. in West palm beach Fl)The fungus restistnat shingles have been on the market for years. (more than 10 that I know of) A roofer may suggest a fungis res. shingle, but once the consumer finds out they are more expensive they usually opt out. As for the copper, that is a good choice, but there again the price is way out of line. (and now days that is mostly used for cosmetic purposes)
 

BadAttitude

New member
OkeeDon said:
I'd be concerned about a copper strip -- doesn't copper turn green and bleed off on surrounding materials?

Believe me, if they thought they could get an extra dollar out of a job by selling special shingles, they'd do it -- unless they've discovered that it doesn't really work.
I'll have to ask one of my roofer bud's about the bleeding...good thing I haven't tried it yet!

That 'get an extra $' deal you mention is a real possibilty. hmm...Makes alot of sense too:4_11_9:

btw Thanks for the links...I saved them last nite, but didn't read yet. It 's on my 'must do list' now:tiphat:
 

BadAttitude

New member
working woman said:
As for the copper, that is a good choice, but there again the price is way out of line. (and now days that is mostly used for cosmetic purposes)
ww
:tiphat:
yep I concur...copper=BIG $$$
Bad enough what the strips costs, don't even want to think about what a coppper sheet roof costs:eek: :smileywac
 

bczoom

Super Moderator
Staff member
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Bump. Did I beat Muley on resurrecting the oldest thread? :)

My roof has been replaced so it's no longer an issue for me but I need to do some work on my Dad's roof which has some "stuff" growing on its North side.

Any thoughts on new approaches or products?

His issue is right near the siding. Will the bleach option discolor the siding? It's a light gray.
 

Doc

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Yep, you get the old post bump award for this one.
This thread was started when FF was one month old. :eek: :yum: :thumb:
 
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