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Never tried to presoak shingles. Have had to use more love when applying just after a rain shower.

The drier the roof the better results. When you're prewetting the roof you're giving the disease a drink of water. You want the disease to soak in the mix instead of repelling it,..as it will do if it is wet with water. Gravity is enough of a hurdle onm it's own,....don't add to the problem by putting water up there before the mix.

If your mix is drying to fast add more surfactant because it adds to the wetting ability of your mix. You can also mist it with water or even a light mix to keep the first application from drying. But spray the roof firtst with your main mix,...and then keep it from drying,...not the other way around.

Jeff

Great post Jeff. I was going to say the same thing.

Pre-wetting the roof dilutes your chemical down also.

Like you said, you want the roof dry so your chemical will soak deeper into the shingles and stick better.

I never wet down my roofs either. I was always scared that giving the algae too much moisture would do the same thing that wetting down the landscaping does.

If the plant survives contact with the chemical because it is already saturated with water then isn't that what is going to happen with the algae too?

I know Dave Westerman had a post about basic roof cleaning procedures where he discussed how wetting down a hot roof was a good thing.

This first time I had ever wet down a roof prior to cleaning it was this year. I cleaned a roof in West Chester Pennsylvania on a house with cedar siding. It had a lot of roof peaks and dormers and I was scared to death of getting spots on that siding. I asked on here how people handled that situation without getting the shingles wet. There was heavy moss right up against every dormer and roof peak and I needed to apply a decent amount of mix right against the siding.

Larry, from All Surface roof cleaning in Palm Harbor FL, convinced me that the Love will still work on a wet roof. He told me to just wet down siding and don't worry about the wet shingles. I took his advice (I still stressed the WHOLE TIME Larry!) and the job went perfectly. I did have to use a little more mix on the wet shingles than I normally do, but it was no big deal.

In general though, I still don't wet down my roofs.


I finally got back out to that house I was referring to with the cedar siding this past Sunday. I had 5 estimates to give in the same area. It is over an hour drive for me so I had been putting off taking the after pictures and then I received all five calls in one week from this area.

I really have to get those after pictures up on here and my site. For anyone that is scared about moss and lichen coming off the shingles after you leave a job, this is a great example. A good portion of the roof was covered with moss and lichen. You can see it in my avitar. The avitar is only a small sample of what was on that roof. I took a picture at almost the same angle and you can see that nothing remains on the roof. It is a great example of the power of these chemicals.

I'll try to do that tonight if I get a chance.

Brian

I only do it if the temp is around 92 - 96 deg out side, I don't like to because I do not want to dilute my love but when it is really humid and hot like it has been these last few days I will lightly spray and cool while we are setting up but once I get up on the roof it is usually dry and ready to go.

My problem is the roofs up her are just soiled heavily.  Like someone took buckets of dirt and dumped them from the trees it came off of.  This is also why we deal with so much moss. Some of these roof tops might as well be flower beds or "organic gardens." In some cases, we have to pre-rinse the roof since this stuff is baked on and any other form would just take too long and cause more harm than good.

I will say that I too have noticed it takes more time and LOVE to work had I not pre-rinsed beforehand. 

Not uncommon having to apply two coats. You shouldn't need to rinse between coats,...just wait for the first coat to dry up some before applying the second coat,...so it absorbs.You can sometimes just mist with water and achieve the cleaning effectiveness of a "second" coat.

Jeff

I'm not a fan of the idea of pre-rinsing, for reasons that Jeff eloquently outlined above.

Am I the only who notices how much worse roof algae looks during and after a rain storm? It seems to just absorb the water and hold it there. I don't know how many of you do extensive scouting of prospective clients, but I have considered either noting where it looks "too wet" to make sure to really focus on cleaning those areas or taking photos while the roof looks so bad to show the homeowner as a "before". Any thoughts?