History of algae-resistant shingles


#1

Hi;

Anyone know how long algae-resistant shingles have been used? Is there a way of telling if existing shingles are algae-resistant?

Thanks,


#2

building supply stores and hardware stores.

A Brief History of Algae-resistant AR-Shingles and What They Are Made-Of
Roofing manufacturers can provide shingles specifically made with an alternative type of mineral granule that resist algae growth. Earlier roofing manufacturers tried an algaecide coating to prevent algae growth. In the late 1980’s manufacturers began using zinc granules but zinc was discontinued out of environmental concerns for using a heavy metal on roofs.

Zinc can also emit a “white rust” that builds up as a white stain or oxide. By 1996 manufacturers were using several coatings on asphalt shingles to reduce algae growth, including cuprous oxide coated granules mixed in with other granules on the shingle surface. The percentage of copper-coated granules (4% up to 10%) affects the resistance of the roof to algae.

Is algae the same as mold on roof shingles? Kirby’s 1996 article confused algae and fungal growth on roofs as equivalent, which may be ok since the same chemicals that resist algae growth may also resist fungal growth and stains. We discuss removing sooty black molds on buildings below. By the way, most of the roof surface samples we have tested (pro-bono in our forensic laboratory) have been shown to be algae, not fungal and not extractive bleeding stains.

Shingle product names that include an “AR” suffix or “3M Algac Block” are products manufactured and warranted to be algae-resistant (OPINION-DF: “algae resistant” doesn’t mean “algae proof”, no?).

hope this answer your question


#3

In the past AR (Algae resistant) shingles was a premium option. The first AR shingle was introduced in the 80’s.

In the 90’s AR became a standard option on most brands.Now I am sure all have the protection.

3M is the actual patent holder on the granules produced to fight the algae.Those patents date back to the 60’s.

One option homeowners and contractors had that was a bit cheaper at the time was zinc strips.The were installed just below the ridgecap.But they were found to have a very short protection span.

Do you have algae/streaks on your shingles?,If you do then chances are they are not AR,If not,they probably are.


#4

“One option homeowners and contractors had that was a bit cheaper at the time was zinc strips.The were installed just below the ridgecap.But they were found to have a very short protection span.”

For real? Is that true? I honestly have no idea or knowledge about that.

I put AR Elks and zinc strips on my roof many moons back, so one or both are still working. I think 13 years, but I’m unclear about it. My roof still looks new, except for a few bullet hole patches.


#5

[quote=“tinner666”]“One option homeowners and contractors had that was a bit cheaper at the time was zinc strips.The were installed just below the ridgecap.But they were found to have a very short protection span.”

For real? Is that true? I honestly have no idea or knowledge about that.
[/quote]

I apologize Tinner I should have been a bit more specific about what caused a shorter lifespan.

When water hits the strip and nail it creates electrolysis which corrodes the zinc strip from around the nail heads.The most common fastener being used is the galvanized nail.

I should have stated that the zinc itself should continue to do its job however the galvanized and the zinc match could cause the failure.Zinc strips supposedly have a lifespan of 40-70 years.


#6

Interesting tidbit. I haven’t checked my nails since they’re under the cap. I only use Maze and haven’t seen any rust stains though. About the best on the market for roofing. About $80. per box.


#7

Saw that Atlas now offers scotchgard shingles that resist algae growth. Carries a lifetime warranty.


#8

“Do you have algae/streaks on your shingles?,If you do then chances are they are not AR,If not,they probably are.”

The shingles in question are on the roof of a friend with an organic farm. He wants to collect rain water from the roof for his crops but only if the shingles do not contain copper (or zinc). His shingles are around 15 years old; in the US.

"In the 90’s AR became a standard option on most brands. Now I am sure all have the protection."
I’ve seen that Owens offers an AR shingle - to me, that means the others are not AR. Right?


#9

if you have certainteed shingle they were the first to use copper coated granuler ,yes after 8 to ten year the algle/streak will still apear on the roof because the zink /copper granuler have lost their effect. ar is just a sale gimmit it slow it down but it don’t stop


#10

AR means they are algae resistant. Read the wrapper because IMO they might stop printing the AR since they are so well known now.But you never know.


#11

lol


#12

Maybe the maze nails you used were double dipped in molten zinc? I just finished a cedar job and 8 boxes cost me over 900.00.


#13

“Maybe the maze nails you used were double dipped in molten zinc? I just finished a cedar job and 8 boxes cost me over 900.00.” Of course. They’re the only roofing nails out there. Oh, and one other brand. Grip-Rite, I think. HDD only for me! No since in using nails that rust off in a few years.
The EG are unsuitable for roofing and only used for tin roofs and felt. Never in shingles.


#14

Yeah, zinc strips can be good if your shingles aren’t algae proof already. Also, you can put some copper wiring around the edges of your roof to help prevent growth. I have seen a lot of San Jose roofing contractors using Atlas Scotchgard protected shingles, which are fortified with copper granules throughout each shingle as well.


#15

[quote=“jkk”]“Do you have algae/streaks on your shingles?,If you do then chances are they are not AR,If not,they probably are.”

The shingles in question are on the roof of a friend with an organic farm. He wants to collect rain water from the roof for his crops but only if the shingles do not contain copper (or zinc). His shingles are around 15 years old; in the US.

"In the 90’s AR became a standard option on most brands. Now I am sure all have the protection."
I’ve seen that Owens offers an AR shingle - to me, that means the others are not AR. Right?[/quote]

They are pretty much guaranteed to contain copper sulfate. The maximum percentage of granules coated will be about 8%. If the shingle packaging does not display the 3M “Algae Block” (prior to 2003) or “Scotchgard” brand, then it could have just about any percentage mix down to almost 0%. In order to use the 3M brand names, the mfgrs must mix it above a certain threshold.

The warranty used to be 10 years, now it is getting bumped up to 20 years.

The stuff of the roof is called algae, in fact is is called “blue-green algae”, but in fact is a bacteria named “gloeocapsa magma”, which eats the limestone filler in the shingles.

All taken together, it’s good for the shingles, but not so good for the organic garden.


#16

I think you should have make your home clean to avoid algae. Hygiene is the best thing to avoid fungus and algae.


#17

i’m actually a roofing contractor that installs atlas roofing’s line of shingles with scotchgard protector. from my experience with other algae resistant shingles, i can tell you that these have the highest concentration of copper and are the only shingles available with a lifetime warranty to protect against roof algae. if you are concerned about preventing algae, these are the only choice at the moment. if you google scotchgard shingles you will find them or just visit atlas roofing’s website.


#18

Hello Everyone,

I may be the scourge of the bunch since I’m a roof cleaning company, but I just wanted to add that no matter what kind of roof you have, it will get dirty and need cleaning at some point. Constant wet and dry daily weather cycles only feed the mold and algae and does nothing to wash away or rinse any of the pollen, dirt, leaves and twigs, insect and animal droppings or anything else that encourages more mold and algae growth.
So, its not a matter of “if”, but “when”. I prefer to use an alkaline cleaning solution with bleach and water. Bleach by itself has too much surface tension and will not get into the nooks and crannies of your roof, whether tile or shingle. Cleaning a roof with bleach only will not last any longer than if you pressure washed it. And you shouldn’t pressure wash ANY type of roof. The cleaning solution immediately begins to neutralize the bleach so once its finished killing everything, within 48 hours its pretty much salt water. Thin clear plastic painter’s sheeting covers most shrubs and plants for a couple of days until the dew runoff from the roof is no longer caustic to plants. Usually, one gallon treats 10 square feet. I use the misters from Ace hardware and set them up on timers to go off at 6am for an hour each morning for the next two days. Third day, I pick up the sheeting, timer, misting hoses, bags and a check. Easy, peazy. No dead plants and roof stays clean for 2 years minimum. Here in Florida, I’ve had some shingle roofs stay clean 5 to 6 years after cleaning them. Tile roofs need cleaning every 3 to 4 years. Shingle roofs need cleaning every 4 to 6 years because of their added algaecidal treatments or mineral additives.


#19

Mrklean,
You say you put the plastic sheeting over the bushes during the process and then for two days after.

What i have experienced is that when i tarp bushes for more than about 4 hours, the top of the bushes get burnt.

You are saying with clear thin plastic sheeting, the top of the plants dont get burnt?