A penny contains only 2.5% copper so I doubt this would have the desired effect.

What about slate roofs? Does the moss effect the slate rock?

David,
Moss does not hurt slate.

Lee Heim,
So long as the pennies liberate some of the copper ions that are on the surface of the penny, not locked inside, they should offer a fairly decent level of protection.

Could you use copper wire?

Janet,
You could, but you need to use a lot of it!

Is the copper strip arranged with the 20% bend up or down?

Hugh.
Down.

To be honest copper and zinc both oxidize and create a patina protecting themselves. Once this happens they don't really release any particles that react with the algae and moss. The best option I've actually seen is a 3-4" galvanized roll. I know your saying yuck/ugly but look at old pipe flashings on roofs, below them the shingles are brighter because that's the original color of the shingles with out the algae/moss. If you look even closer though another 5-10' below that it's not affected. The strips work well for a few feet but beyond that it just peters out. Even the shingles with algae blockers only carry a 10yr prorated warranty. The copper granules don't work forever. Maintenance at least once a year is your only real option. A product out of Eugene,OR has worked the best for me. It's messy to install requires a special sprayer and it's expensive but it works and continues to work for several years. It's called Dennco. Shingle Shield works ok also but the Dennco has worked the best for me.
Thanks,
Dan

Dan,
To be really really honest, your second, third and fourth statements are *wrong*. The metals do oxidize which produces the patina you correctly describe. But the metals do *erode* and the CuO2 or ZnO2 do wash down onto the roof. You are also wrong about how far down the roof the chemistry works. On my garage roof there is no vegetation from the peak to the gutter line, a distance of 15 feet. Furthermore, I have seen protection as great as 35 feet on institution roofs. There is no maintenance. The copper on my cupola has kept the garage roof moss and algae-free for over 15 years with no effort on my part.

Wow your lucky. Here in Oregon it just doesn't seem to work that way. I put a hug 24" copper piece under a tile ridge and it still is growing algae and moss. I feel bad for the home owner, that stuff is expensive.

Dan,
We would love to see a photo of this. I will post it with your permission. Did you clean the roof of all moss and algae just before you installed the copper? That has to be done......

I'm still confused as what to use to clean my roof, it has had blk steaks that has been getting bigger every year. Had no idea it was mold. Does the oxygen solution work as well as the commercial products?
Also, to get back to the penny thing, How many pennies and how would you arrange them? Like evey other shingle or strait along the roof line?

How will the dissolved copper affect plants that I want to grow beneath the eaves of my garage?

this was just the information I was looking for - thanks! someone told me that I could dissolve copper sulfate and spray that on - would that be better than the OxyClean type product to knock the algae down?

Pennies minted before 1982 are 95% copper (5% zinc), so go to the bank and get a few rolls and sort out the older cents.

Just don't use the "wheat back" cents (1959 and before) unless you want coin collectors sneaking onto your roof--some of them are actually worth significantly more than face value. :)

Hi. Would Oxygen bleach be suitable for clear fibreglass verandah roof panelling - we have black moss growing on it.

I have a roll of 15" wide copper flashing. If I cut strips of this, how exactly would I attach it to my roof. Should I nail it under shingles? Thanks for any directions how to attach this copper flashing to my roof. My roof has a good amount of moss that has got to go.

Can you just pressure wash the roof to get the moss off, instead of scrubbing it?

Hello Tim, I've been trying to find the specific tool you mention to put the bend in the copper strip, but I can't tell what it is. I can't find anything that looks like it would put the bend in consistently.

Can you give me any more detail?

Thanks,
Bryan

You did not mention power-washing as a means of removing moss and algae. Is this an advisable procedure, or will it damage asphalt and other types of shingles?

Henry,

Tim did a video on power washing your roof. Check it out. http://www.askthebuilder.com/How_to_Pressure_Wash_Your_Roof_Video.shtml

I've just finished cleaning moss, green (rosetta-shaped) lichen, grey lichen and even a few spots of yellow lichen/algae from a light tan/brown composition roof. It was a sunny, dry day with air temps around 80 and little humidity. The roof was probably around 120 degrees and the growth on the roof was tinder dry. At first I tried a stiff brush which had little to no effect on the lichen or long moss, although it did dislodge the "puffy" type moss balls. So I switched to a wire brush/scraper and "rinsed" off with a Toro electric air blower. I know wire brushing did damage to the shingles but letting the crud multiply was even worse. This roof is odd in that most of the shingles don't adhere to each other so air-blowing the dust and dirt off the roof also lifted the shingles up with the inherent risk of cracking, breakage. Pressure washing would likely have bust a lot of these shingles! It's an old beach cabin that over the years has been changed and expanded into a year-round dwelling with differing roof pitches, directions and shapes not to mention 9 skylights and numerous vents (ridge, fan extraction) making for an obstacle course of a roof. It's also nestled amid and beneath a whole bunch of medium growth trees.

There are parts on the S. side of this roof where the shingles are curling and falling apart with lots of black patches where the tan particles were dislodged. These shingles are obviously the oldest and at the end of their life. Other areas of the roof are almost brand new while still others are of differing ages, some with lichen and moss (N. side) while other sections are clean. I know I'm not the first up there to clean, either.

Upon scraping/brushing away the lichen on the N. side the damage to the shingle underneath was obvious. The worst lichen was the green, rosetta shaped, "heavy duty" type which "ate" the particles from the shingle leaving black circles behind. Lichen DEFINITELY did damage to these shingles while the moss didn't. So even though the mosses undoubtedly held more water than the lichens there was less damage to the roof (with wood shingles this probably wouldn't be the case.) I would say lichen "feeds" off something in the shingle or at least has a root system that disrupts the embedded particles in the surface of the shingle. After this lesson I will never allow lichen to grow on my own roof which is still in good shape at 7 /yrs. old!