I might give this a try. I've tried the Tide with bleach, and it didn't do much other than turn the moss slightly brown for a few weeks. I suspect though that with how wet our winters are, any chemical solution would have to be reapplied every couple of weeks to be effective. In a normal winter here, my roof is pretty much continuously wet from mid November until late March. Our days are so short in that time period that even if we do get a couple of dry days in a row, the roof doesn't dry out.
Seriously? We have at least one in every city, not to mention every tool store, auto parts store, and industrial supply store stocks pressure washers and parts.
I made two applications 90 days apart to get rid of my years of built up moss and stains. Now I am on once per year application in spring. Remember ......this is a lesson in patience It does take at least 90 days to work.......if it's thick, W&F it will kill it, so gentle hose washing might be needed, if it rains really hard the moss will roll into the gutters. As others have stated I would never use a pressure washer on a asphalt shingle roof. The shingle granules are critical for shingle life any thing that removes the granules is bad.
Was this in Wausau? If so, I think you have a very different climate than we have. We average 185 days with precipitation / 225 cloudy days per year, and in the wintertime frequently go more than a month without any sunshine. In this area the moss grows on everything, like this:
my neighbors house has a good 1-1/2" little roll of moss on every edge of every shingle. I cant bring myself to tell him he needs to do something about it, or keep letting it go and risk a leak. maybe if he was on advrider i could tell him We live on the north face of a hill, with huge timber way up high behind our houses. wintertime never brings the sun to our house. it's always 5-10 degrees cooler than the little shopping center down the hill about 7 blocks away
Yes I have a very different climate -30 to 100 and a full four seasons ..........if it fixes your moss problem .............you will be the poster boy for WET and Forget Take before and after picture ........... ....if it works F&G should pay you for an endorsement.
That picture was actually taken at a campground about an hour from my house, but I do have woods behind my house that are almost that mossy. My roof is currently a lot cleaner than that right now though, since it was pressure washed last summer... I will give the Wet and Forget a try though, I've already got moss building up again in the more shaded areas of the roof, and given the age of my roof, it would be good if I can be gentle on it and squeak a few more years out of it...
String a piece of copper wire along ridge on both sides...(non insulated)..problem solved... Or, replace the top row of shingles, under ridge with galvy metal..problem solved... Application of bleach every couple weeks cleans a moss ckveted roof up well. To give folks an idea, i have to use bleach water to wash my truck, as the shady side grows algae, between washings....:eek1
Late to the discussion here but........Asphalt shingles utilize stone or ceramic granules which are applied during the manufacturing process as a top coat. These granules not only provide color to the shingle but also serve to protect the shingle against UV degradation and helps assist in protecting against wind uplift (by adding weight). When one power washes the shingles, you remove granules and expose the underlying asphalt base to UV and higher temperatures thus causing accelerated deterioration as well as decreasing the weight of the shingle thus shortened life expectancy with increased potential for storm related damages (insurance companies have figured this out, another topic some time). In addition to this, one should never ever power wash a wood shake or shingle roof as the pressure of the water damages the wood fiber cells causing them to split. Once split, water seeps in, keeping the wood wet from the underside and not being able to completely dry out. Best bet....as outlined earlier, install a copper or zinc strip the width of the roof, sticking out several inches from a course of shingles, near the ridge and keep trees trimmed back from the roof so as to allow the shingles to completely dry out after a rain.