Need ideas on cleaning my roof

I have an white asphalt roof that has several black algae streaks. As a test I sprayed 1 with a mixture of bleach and Jomax House Cleaner. The stain came off but it took repeated sprayings of the solution (per the Jomax label). I used Jomax House Cleaner because I did not know there was a Jomax Roof Cleaner and my local HDW store only stocks the house cleaner. It is probably the same product.
For convenience, does anyone know of a sprayer that I connect to my garden hose? I was thinking of a garden sprayer like they sell to spray Ortho chemicals onto trees. But what setting would I set the sprayer to adjust the concentrate of the Jomax/Bleach mix?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
higgledy wrote:

    I hope you have better luck than I did. I used a tank sprayer to soak the shingles with a mixture of Jomax and Bleach. After it had set a while, I used a pressure washer on a low setting to clean the shingles. (You can damage the shingles if you use too much pressure.) It cleaned them, but when I noticed that every house around me had the same problem I did, I said this is a losing proposition. I believe the fungus would simply start again from airborne means.
    It could easily become a career choice, and not one I would want.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ken,
You are correct that it will only start again but I need to replace a few shingles anyway. While I am up there I am thinking about installing zinc or copper flashing near the top to act as a algaecide. I need to check on pricing of the flashing to see if it is not crazyily expensive. My house is only 10 years old, the builder put the cheapest shigle possible even though the neighborhood is built on a windy ridge. What an f'er. Anyway, I cannot afford a $10k new roof right now so I need to do what I can to make my house look decent. It is a rancher with a white-tall pitched roof. The streaks make the whole look like trash.
Ken wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
try pure full strength bleach
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
higgledy wrote:

    For what it is worth, I originally had black shingles on my house and replaced them with lighter colored ones so as to reflect some sunlight on the roof. When I replace the shingles the next time I am going with a dark shingle in order to minimize the impact of the stains.
    One other comment: A couple of the homes in my area (Mid-south) attempted to stop such problems with the zinc strips after re-roofing their homes. From my observation their attempt was not successful. It might have had some impact, but they did not rid their roofs of the stains.
    If someone ever invented a shingle that would prevent such stains from developing, he would be a very rich man. I know there are some that claim some success, but I do not think any work 100%.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I did learn of this chemical treatment: www.anti-growth.com
Does anyone have any experience with it?
Ken wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sheesh. From This Old House:
"The black mold-like stains and streaks that appear on roofs, particularly light-colored asphalt shingles, is actually a blue-green algae (Gloeocapsa magma). Commonly found in climates with warm, humid summers, it does no damage to the roofing, but it certainly does looks bad.
You could replace all the roofing with new shingles dark enough to disguise the staining, or with shingles laced with copper granules, which are lethal to algae. But that would only make sense if the shingles were worn out.
The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae. (No pressure washers, please. They're likely to damage the shingles.) Just be sure to wet your foundation plantings first, and rinse everything in clean water when you're done. Plants don't like bleach, and wetting them with plain water first protects them.
To keep the algae from coming back, insert 6-inch-wide strips of zinc or copper under the row of shingling closest to the roof peak, leaving an inch or two of the lower edge exposed to the weather. That way whenever it rains, some of the metal molecules will wash down the roof and kill any algae trying to regain a foothold on your shingles.
You can probably see this same principle working on roofs in your neighborhood. Look for chimneys with copper flashing; the areas directly below the flashing will be free of any algae stains.
The strips also work on roofs suffering from moss buildup. Just scrub it off first with a brush, then bleach as above. "
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.