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CeliaP
Moss on roof
CeliaP

Went to home show over the weekend hoping to view some bathroom fixtures but all I got was contractors selling their services. One of them was for clearing moss and mold off roof. My roof does have moss on it so I got a quote. Now my question is - do I really need to worry @ the moss? The roof is @ 10 yrs old - only the one layer. When we replaced the roof the new shingles were supposedly moss resistant (I would have to check if there is a warranty @ the moss). Nothing is leaking of anything but parts of the roof definitely have moss. The area is shady and we're not planning to cut down all the trees so it will continue to be shady. So do I need to worry @ the moss impacting the durability or waterproofing of the roof?

dj1
Re: Moss on roof
dj1

I'm pretty sure that moss will shorten the optimal life of the roof. One old method of cleaning moss off the roof is to power wash - trouble is: power washing shortens the life of shingle roof even more!

Forget what you saw in that home show.

The best and cheapest way to kill the moss is: use bleach (undiluted - a gallon of bleach for 100 sf) with a garden sprayer.

Wait 20 minutes and watch the moss disappear.

Caution: if you are not comfortable walking on the roof, let a handyman do it.

Fencepost
Re: Moss on roof
Fencepost

Another product you can buy at most hardware stores is a powdered zinc-based compound. You sprinkle it along the ridge and let the rain wash it down. If you have a lot of moss, it may take a few applications at least a month apart.

GregJ
Re: Moss on roof
GregJ
dj1 wrote:

I'm pretty sure that moss will shorten the optimal life of the roof. One old method of cleaning moss off the roof is to power wash - trouble is: power washing shortens the life of shingle roof even more!

Forget what you saw in that home show.

The best and cheapest way to kill the moss is: use bleach (undiluted - a gallon of bleach for 100 sf) with a garden sprayer.

Wait 20 minutes and watch the moss disappear.

Caution: if you are not comfortable walking on the roof, let a handyman do it.

Tommy suggested a 50/50 solution of bleach and water. Is this adequate for a moderate black mold/algae? Should the roof be dry before applying and should it be rinsed off? Thanks

dj1
Re: Moss on roof
dj1
GregJ wrote:

Tommy suggested a 50/50 solution of bleach and water. Is this adequate for a moderate black mold/algae? Should the roof be dry before applying and should it be rinsed off? Thanks

A 50/50 solution may be too weak for most moss. Don't forget, this moss develops a significant root system on the roof. My approach is aggressive enough to kill the moss, and it's not that more expensive. Besides bleach, they have other chemicals at the stores, but bleach is the most economical solution.

Dry roof is better. If the roof is a little wet, then your bleach will not be 100% anymore. Still good though.

If there is no rain in the forecast, go ahead and wash the roof. Usually a moderate rain can do a pretty good job of rinsing.

Condoman
Re: Moss on roof
Condoman

I had agreed to help a friend in getting rid of moss on the roof that had been a year or so growing. We decided to try Wet-N-Forget for an area that could be reached by hand pump sprayer without going on the roof. It is a very steep roof and I am too old to be that stupid.

After a few weeks we could see progress in that the moss was turning brown. Weeks later most of the moss was gone and the brown remains had blown or was washed off by the rain. This left a majority of the roof still with moss because it was near the peak and way too high to reach by sprayer.

I researched several delivery options and we settled on a system of an inexpensive submersible pump in a 5 gallon bucket with the appropriate water/Wet-N-Forget mixture connected to 25 feet of 1/4 inch poly tubing with a shutoff to control flow. This was run through two 10 foot sections of 1/2 inch electrical conduit connected together. At the roof end was a small 3 wheel dolly attached to assist in moving the pipe across the roof.

I applied about 15 gallons of Wet-N-Forget over several weeks. By then it was fall and we stopped working on the issue until the spring.

Upon arriving the next year I could see the entire roof was free of moss and brown remains. If I had not done this myself I would not have believed it was possible. The up side of the product is no damage to plantings or us as we worked in the down hill side of this application. And of course no ladder climbing.

dj1
Re: Moss on roof
dj1

It's good to know that wet n forget worked for you. My only question is why it took so long to activate.

I don't know what you paid for 15 gallons of wet n forget ($30 a gallon?), but I know that generic bleach is dirt cheap,

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