Ridding roofing of moss?

[Fred Voorhees]

Hey guys, I was out in the yard today and noticed just how much moss has grown on my outdoor shed roof on the North side. I know that mixing chlorine bleach with water and sprayed on the offending stuff will rid it, but does anyone know the approximate ratio of bleach to water? I have a garden sprayer that I can use, I just need to know the proper mixture ratio, or any other suggestions if anyone has any. Thanks

[Michael Gibbons]

I would guess maybe a 1/4 cup to a gallon would work and after you get it cleaned, keep it that way . Do you have a lot of trees or bushes that drop stuff on the roof? Is it quite shady where your shed is? I'd probably try and find a way to keep the dirt from acumulating on top and I think that would work better than all the bleach you could find. You also might trim some branches away so some light could hit the roof and dry it out.

[Joe Pelonio]

Moss on the roofs is a huge problem here. Some people buy the commercial stuff to treat it, some use Tide laundry detergent. Just yesterday I noticed 2-3 roofs with white all over them.

[Ken Fitzgerald]

I often buy some bagged crystals for this purpose at the local garden center or BORG. Sprinkle the crystal up near the peak of the roof and water it down.

[Jim King]

Swimming pool chlorine is cheap and a pound will make 20 gallons of very strong bleach.

[Cliff Rohrabacher]

Do you have a lot of trees or bushes that drop stuff on the roof? Is it quite shady where your shed is? I'd probably try and find a way to keep the dirt from acumulating on top and I think that would work better than all the bleach you could find. You also might trim some branches away so some light could hit the roof and dry it out.

What he said. It needs sun shine.

[Von Bickley]

I buy the cheapest bleach I can find at the grocery store and mix 1 part bleach to 3 parts water. Works GREAT for me.

[Lee Schierer]

I've heard that strips of zinc near the peak will prevent moss from groing on a roof. The zinc washes off evry time it rains and kills the moss that is lower down on the roof.

[Tom Pritchard]

Fred, I wouldn't recommend bleach, as many roofing experts agree that it will leach tar out of your shingles and make them brittle. Here's the process I used to remove moss from my shed roof and it worked great!

It is wise to avoid chorine bleach as a roof cleaner.

A better roof cleaner might be non-toxic oxygen bleach. This widely available powder is mixed with water and applied to a cool roof surface, preferably on an overcast day. If you keep the roof surface wet with the solution for just 20 minutes and then lightly scrub the roof surface, the algae almost always comes off. Severely stained roofs may require multiple applications of the oxygen bleach solution. The solution also helps to loosen the grip of the shallow moss roots.
Once the roof is clean you can hinder moss and algae growth by introducing copper onto the roof surface.Visit a roofing supply company that sells tin, copper and galvanized metal products to residential customers. Often these companies sell rolls of copper that can be cut into long strips. I like to cut strips that are 5 or 6 inches wide and are ten feet long. Using a metal brake tool, I put a 20 degree bend one-half inch in from the edge on one of the long sides of the copper strip. This bend eliminates unsightly waviness that often develops as you cut the copper with a tin snips.
Place these strips of copper near the top of the roof. Slide the unbent edge up under a row of shingles so that the bent edge and 4 inches of copper is exposed to the weather. Each time it rains some copper molecules wash down onto the roof and create a poisoned environment that both the moss and algae dislike. Be patient as the copper eventually will turn a distinctive dark brown and then the classic green color. If you getting ready to install a new asphalt shingle roof, be sure to buy shingles that have copper hidden in the colored ceramic granules.
Cleaning roofs can be dangerous work. Algae that becomes wet is often as slippery as wet ice. Try to work on dry parts of the roof and reach sideways to scrub and clean those parts of the roof that are wet with cleaning solutions. Once a roof is clean, they often are not too slippery if they are wet. Wear shoes that have excellent traction. Sitting and working on the roof instead of standing lowers your center of gravity and minimizes your chances of falling from the roof.
The copper material works far better to poison roofs than zinc. Zinc is indeed effective, but copper tends to do a better job for a longer period of time. The copper strips are easy to install and they tend to blend into the roof once the shiny copper begins to oxidize and turn the distinctive dark brown.

[Joe Pelonio]

A better roof cleaner might be non-toxic oxygen bleach. This widely available powder is mixed with water and applied to a cool roof surface, preferably on an overcast day.

The stuff that annoying "Billy" guy sells on the TV commercials?

[Tom Pritchard]

The stuff that annoying "Billy" guy sells on the TV commercials?

No, I just bought some Oxi-wash at our local grocery store.

[Russ Filtz]

Same stuff. I use oxyclean for all kinds of things, from laundry to steam cleaning carpets. I used it once to get water stains out of a 50-yr old flag with no fading (pretty nervous about that one, dry cleaning had failed already!)

[John A Walker]

Hey guys, I was out in the yard today and noticed just how much moss has grown on my outdoor shed roof on the North side.

Reckon it's time you turned your shed around Fred.

Just my warped sense of humor my friend!

Seriously, I wish the air over here was clean enough to allow moss to grow anywhere. (Or is that lichen I am thinking of?)

Can you not buy proprietory brands of moss-killer in the States? Or is it banned for some reason?

Best

John (UK)

[Rich Engelhardt]

Hello Fred,

Have a look here:
www (dot) ashphaltroofing (dot) org
They have a PDF on alge under the tech bulletins.

We went with GAF shingles on our house last fall after looking into all the different mfg's of shingles.
GAF was best overall from what I could glean from peoples experiences with all the brands I could track down on the web.

Washing off the "moss" is only a temporary fix. For a more permanent fix, you need to replace the shingles with ones that will resist the growth in the first place.
Depending on the size of the shed roof, it might be just as easy to simply replace the shingles and be done with it instead of having to clean them every so often.

[Kyle Kraft]

I'd try the zinc strips installed a couple courses down from the ridge. My mom is a tree lover (I'm a lumber lover ), and she has all kinds of trees overhanging her roof. The north-facing roof slopes had moss-algae-green-perscunnion stuff on them, and she installed the zinc strips when the roof was redone, and no more growth.