Cleaning shingles (moss & mildew)

Questions on how we spend our money and our time - consumer goods and services, home and vehicle, leisure and recreational activities
Post Reply
Topic Author
Broken Man 1999
Posts: 2173
Joined: Wed Apr 08, 2015 11:31 am

Cleaning shingles (moss & mildew)

Post by Broken Man 1999 » Wed Apr 10, 2019 1:56 pm

Our 13 year old roof is, well, ugly. No physical issues other than mold/mildew/moss. I had the main roof inspected by the builder of my home about a year ago when I had a metal roof put on our sun room and breakfast nook, all was well. But, it is ugly.

The current roof is 40 year Owens-Corning architectural shingles installed in 2006. I don't expect them to last 40 years, but I hope to have 10-15 years left.

I am hoping I can get them looking a bit better by getting rid of the mold/mildew/moss that is discoloring them. One problem for the roof is it is mostly under a nice shady canopy of mature oaks, very good growing conditions for nasty stuff. But, we do love the shade.

Anyone have any experiences with cleaning shingles, positive or negative?

Rough costs? I'm sure the cost would vary by area. I live inland on the west coast of Florida, east of Tampa.

Thanks!

Broken Man 1999
“If I cannot drink Bourbon and smoke cigars in Heaven than I shall not go. " -Mark Twain

User avatar
RickBoglehead
Posts: 2887
Joined: Wed Feb 14, 2018 9:10 am

Re: Cleaning shingles (moss & mildew)

Post by RickBoglehead » Wed Apr 10, 2019 1:58 pm

People have had success spraying Wet and Forget.

If that doesn't do it, you can look into a product called Jomax, which you mix with bleach and apply, then rinse off. It would require application from someone on the roof, Wet and Forget can be applied from a hose end sprayer.
Avid user of forums on variety of interests-financial, home brewing, F-150, PHEV, home repair, etc. Enjoy learning & passing on knowledge. It's PRINCIPAL, not PRINCIPLE. I ADVISE you to seek ADVICE.

Yooper16
Posts: 184
Joined: Mon Aug 21, 2017 7:44 am

Re: Cleaning shingles (moss & mildew)

Post by Yooper16 » Wed Apr 10, 2019 2:01 pm

Ditto on Wet and forget. It will probably take a couple to a few weeks for it to do the job, as the carton says but they will look almost new when done.

corysold
Posts: 771
Joined: Mon Mar 24, 2014 12:58 pm

Re: Cleaning shingles (moss & mildew)

Post by corysold » Wed Apr 10, 2019 2:28 pm

Wet and Forget does work, I used it on my roof on a similarly shaded spot.

Though the moss all died, it took quite a while for it all to be washed from the roof with rain and such. Depending on whether that will bother you, you may want to look for a solution to removing it once it's dead.

DetroitRick
Posts: 654
Joined: Wed Mar 23, 2016 9:28 am

Re: Cleaning shingles (moss & mildew)

Post by DetroitRick » Wed Apr 10, 2019 2:35 pm

I've had good luck with a product called "Spray & Forget Super Concentrated Roof Cleaner". They have many formulations, but I use the one formulated particularly for roofs. Covers mold, mildew, algae, etc. No brushing, rinsing or agitating. Works long after application. Luckily for me, the 20-foot spray nozzle allows me to hit the whole roof from a ladder at gutter level. Expensive, but it's worked well for on my place. Because this is an issue here on northern side only, one bottle costs around $42 and is sufficient for that half of roof (not sure on roof measurements, but house is 1450 sq ft ranch).

When I applied it on my former/older heavily stained shingle roof, it took a while to really improve things. After a year, and a reapplication, noticeably better. Two years on, stains 100% gone. On my current, now 14-year old shingle roof (GAF, architectural), I used it at first trace and reapplied the following year. No staining at all.

I suspect these products are highly regional. In my area of Michigan, this type of staining is extremely common on the northern side of our roofs. Even on most new roofs at the 10 year mark. Because you are in Florida, different climate, I'd probably talk to a few folks in your immediate area to see what works best there.

I get it from my local hardware store for just over $40, but haven't yet seen it at the big boxes. Amazon has it for $39.95, although w/o the 20' sprayer (garden sprayers - non pressure - would work fine in that case).

User avatar
wageoghe
Posts: 533
Joined: Wed May 25, 2011 8:28 am
Location: Northern Alabama

Re: Cleaning shingles (moss & mildew)

Post by wageoghe » Wed Apr 10, 2019 3:07 pm

Some people advocate using copper or zinc strips/flashing (tucked under shingles high up on the roof with some amount of the strips/flashing exposed) to control algae and moss on a roof. I don't know if it is effective or not. If it is, a bonus would be that it should prevent algae and moss going forward. I'm sure this would cost more than just spraying on some Wet and Forget but, if it works, it means you probably would not have to think about your roof problems again (until you have to replace your roof).

Wilderness Librarian
Posts: 132
Joined: Sat Jun 23, 2018 8:50 pm
Location: Idaho

Re: Cleaning shingles (moss & mildew)

Post by Wilderness Librarian » Wed Apr 10, 2019 6:28 pm

Admittedly I have no idea what such a roof might look like in Florida. But before you do anything you might want to check your public library to see if they have a copy of "Gathering Moss: a Natural and Cultural History of Mosses" / by Robin Wall Kimmerer. I read this a couple of years back and it is fascinating. The author has a PhD in bryology (or whatever the study of mosses is called I realize my spelling is bad) but grew up in a Native American culture and has different chapters drawing from both perspectives. The book as a whole is semi-technical with lots of Latin species names and references to the author's personal research and experiences. But there is one non-technical chapter you really must read regarding urban mosses. After doing so you might decide your problem is that you don't have enough moss especially given your comment about a nice shady canopy of mature oaks. Seriously though the author quotes a person whose job it is to de-moss roofs that the moss causes no damage and may actually protect the roof and they do not understand why anybody would pay to de-moss (and that is their job!). I realize you are looking at this as a primarily visual aesthetic matter and that may override the above. But my overall reaction to the book was WOW - not only eye opening but a book you really have to read twice to read once.

User avatar
WestUniversity
Posts: 182
Joined: Sat Oct 07, 2017 7:27 am

Re: Cleaning shingles (moss & mildew)

Post by WestUniversity » Wed Apr 10, 2019 9:42 pm

Yooper16 wrote:
Wed Apr 10, 2019 2:01 pm
Ditto on Wet and forget. It will probably take a couple to a few weeks for it to do the job, as the carton says but they will look almost new when done.
+1

cudavid
Posts: 7
Joined: Thu Feb 14, 2019 7:57 pm

Re: Cleaning shingles (moss & mildew)

Post by cudavid » Wed Apr 10, 2019 9:53 pm

Buy copper sulfate on eBay , mix with hot

water, pump sprayer on roof, works great, low cost

bhsince87
Posts: 2183
Joined: Thu Oct 03, 2013 1:08 pm

Re: Cleaning shingles (moss & mildew)

Post by bhsince87 » Wed Apr 10, 2019 10:00 pm

I like the look of moss on our roof, so I just let it grow.

Most data I've seen is mixed on whether it damage/helps/has no effect on asphalt shingles.

That being said, there is a period of a few years before the moss grows over the mildew that's not very pretty.
Retirement: When you reach a point where you have enough. Or when you've had enough.

Topic Author
Broken Man 1999
Posts: 2173
Joined: Wed Apr 08, 2015 11:31 am

Re: Cleaning shingles (moss & mildew)

Post by Broken Man 1999 » Thu Apr 11, 2019 3:23 pm

Thanks for the tips. I need to talk to a neighbor and see if he can do it. He is retiring next month, and he is kinda a neighborhood handy man. He works in his own time, but I have a feeling he is going to go stir crazy if he can't find some things to do. I have a couple of projects for him if he is interested.

I need to pull out my paperwork on my roof and see what is in it, as well.

Just for grins I'm getting some estimates for the service.

Broken Man 1999
“If I cannot drink Bourbon and smoke cigars in Heaven than I shall not go. " -Mark Twain

likegarden
Posts: 2793
Joined: Mon Feb 26, 2007 5:33 pm

Re: Cleaning shingles (moss & mildew)

Post by likegarden » Thu Apr 11, 2019 5:09 pm

Last year I had a local house washing business wash our 20 year old roof shingles and the house walls, but not the windows. They did it nicely for $600 in a few hours on a warm February day in the Northeast. They used something like Spray and Forget and said the full effect could be seen after some time. Our roof eaves had developed dark lines on their white color, and now they are fully white again. I am retired and do not dare any longer going up on the second floor roof.
Last edited by likegarden on Fri Apr 12, 2019 7:25 am, edited 1 time in total.

shunkman
Posts: 49
Joined: Mon Feb 26, 2018 9:59 pm

Re: Cleaning shingles (moss & mildew)

Post by shunkman » Thu Apr 11, 2019 5:57 pm

I simply use a 50/50 bleach/water solution in a garden sprayer. After spraying, the moss died, dried out, and washed off on its own. I also removed the tree that was shading that area of the roof.

shunkman
Posts: 49
Joined: Mon Feb 26, 2018 9:59 pm

Re: Cleaning shingles (moss & mildew)

Post by shunkman » Thu Apr 11, 2019 6:28 pm

bhsince87 wrote:
Wed Apr 10, 2019 10:00 pm
I like the look of moss on our roof, so I just let it grow.

Most data I've seen is mixed on whether it damage/helps/has no effect on asphalt shingles.

That being said, there is a period of a few years before the moss grows over the mildew that's not very pretty.
The roots of the moss grow under the singles and then eventfully lift the shingles. I strongly suggest eliminating the moss.

3504PIR
Posts: 718
Joined: Mon Jul 26, 2010 2:46 am

Re: Cleaning shingles (moss & mildew)

Post by 3504PIR » Thu Apr 11, 2019 7:26 pm

When we lived in FL I pressure washed our roof where we had similar moss. I would try the sprays first but if they don’t work, you can pressure wash on a moderate setting. In FL we had a gas pressure washer as I was regularly doing the drive, lanai or around the pool.

Plus 1 on tree removal. We lived in Gainesville and cleared all the trees over the roof and it saved our home during several hurricanes.

Nowizard
Posts: 1861
Joined: Tue Oct 23, 2007 5:33 pm

Re: Cleaning shingles (moss & mildew)

Post by Nowizard » Thu Apr 11, 2019 9:26 pm

Two issues: 1. What to use, 2. Who to use it. For me, getting on the roof is not worth the risk. We used someone with a pressure washer. It cleans the dirt and would remove heavier objects such as the moss that will adhere to the shingles more than the dirt. Costs $400-500 in our locality for a 5,000 sf house.
Tim

User avatar
Elric
Posts: 111
Joined: Sat Dec 08, 2018 12:23 am
Location: Virginia
Contact:

Re: Cleaning shingles (moss & mildew)

Post by Elric » Thu Apr 11, 2019 9:32 pm

Another vote for Spray and Forget. I haven't tried Wash and Forget, a rival brand. Spray and Forget removed moss growing on our roof, as well as other organic stuff that was darkening it. The nice think is you just need enough water pressure from your hose to reach the area. The moss won't disappear or wash off immediately, but it will die off and eventually the rain will wash it away.

One caveat: the label says if you wash your plants before and after, it won't damage plants. I found it DID damage one type of my shrubs. If I use again in the same area, I'll cover them.
"No man is free who works for a living." | Illya Kuryakin

Topic Author
Broken Man 1999
Posts: 2173
Joined: Wed Apr 08, 2015 11:31 am

Re: Cleaning shingles (moss & mildew)

Post by Broken Man 1999 » Fri Apr 12, 2019 8:22 am

3504PIR wrote:
Thu Apr 11, 2019 7:26 pm
When we lived in FL I pressure washed our roof where we had similar moss. I would try the sprays first but if they don’t work, you can pressure wash on a moderate setting. In FL we had a gas pressure washer as I was regularly doing the drive, lanai or around the pool.

Plus 1 on tree removal. We lived in Gainesville and cleared all the trees over the roof and it saved our home during several hurricanes.
Our little subdivision is full of beautiful oaks, for a portion of the street the canopy has grown completely over the street.

In my area, one cannot remove certain types of trees, including oaks, unless they are diseased and pose a threat of falling. And, in the area where a daughter lives, for new construction you have to have trees, and I think the regs state oaks, but definitely not palm trees.

But, even if it were possible to remove the trees, the neighbors would rise up and run us out of the neighborhood, and rightfully so. And, shade is a plus for the Florida heat.

We do keep the trees cleared of dead branches, and trimmed back. We trim them every couple of years, last year we trimmed right before the hurricane that devastated Havana Beach came calling.

Broken Man 1999
“If I cannot drink Bourbon and smoke cigars in Heaven than I shall not go. " -Mark Twain

jasg
Posts: 93
Joined: Wed May 08, 2013 7:10 pm

Re: Cleaning shingles (moss & mildew)

Post by jasg » Sat Apr 13, 2019 10:33 am

A family member used to live in your area and a zinc strip under the ridge shingles does wonders - but roofers hate to install them. They would rather your roof last for a shorter time...

Another approach is to put down a line of Arm & Hammer washing soda (sodium carbonate from the laundry aisle or from a pool supplier). As the rain washes it down, it creates a very basic environment that moss/mildew can't tolerate. Just do this every year along the ridge line and midway if you have a large roof. I do this annually to fight the moss in the PacNW.

I don't like pressure washing - around here they use an air compressor to blast off the moss. Less damage to shingles.

Topic Author
Broken Man 1999
Posts: 2173
Joined: Wed Apr 08, 2015 11:31 am

Re: Cleaning shingles (moss & mildew)

Post by Broken Man 1999 » Sat Apr 13, 2019 1:22 pm

jasg wrote:
Sat Apr 13, 2019 10:33 am
A family member used to live in your area and a zinc strip under the ridge shingles does wonders - but roofers hate to install them. They would rather your roof last for a shorter time...

Another approach is to put down a line of Arm & Hammer washing soda (sodium carbonate from the laundry aisle or from a pool supplier). As the rain washes it down, it creates a very basic environment that moss/mildew can't tolerate. Just do this every year along the ridge line and midway if you have a large roof. I do this annually to fight the moss in the PacNW.

I don't like pressure washing - around here they use an air compressor to blast off the moss. Less damage to shingles.
Interesting idea, using Arm & Hammer washing soda, first I've read about that. I'm not sure if that would work on my roof, as it is pretty steep. So far as pressure washing, that would be my absolute last choice, as I would fear damage by overzealous washers.

Sounds like the gentle application of some of the products mentioned should be tried first.

Thanks!

Broken Man 1999
“If I cannot drink Bourbon and smoke cigars in Heaven than I shall not go. " -Mark Twain

User avatar
MP123
Posts: 881
Joined: Thu Feb 16, 2017 3:32 pm

Re: Cleaning shingles (moss & mildew)

Post by MP123 » Sat Apr 13, 2019 7:07 pm

jasg wrote:
Sat Apr 13, 2019 10:33 am

Another approach is to put down a line of Arm & Hammer washing soda (sodium carbonate from the laundry aisle or from a pool supplier). As the rain washes it down, it creates a very basic environment that moss/mildew can't tolerate. Just do this every year along the ridge line and midway if you have a large roof. I do this annually to fight the moss in the PacNW.
That's what I do with "Moss Beware". It's basically powdered zinc sulfate. Line it down the roof ridge and let the rain wash it down both sides. It takes a few weeks to kill the moss but lasts all year. Once it's dead you can brush it off with a broom pretty easily. Works well in the NW, not sure about your Florida moss.

Are there access issues with the roof or is it pretty easy to work on?

User avatar
nativenewenglander
Posts: 113
Joined: Sun Jul 30, 2017 6:05 am

Re: Cleaning shingles (moss & mildew)

Post by nativenewenglander » Sun Apr 14, 2019 5:02 am

We used Pool Shock and water with some dish soap on my dad's roof it worked great. You can Google it and get the right mix as I don't remember now.
It took a couple gallons of Pool Shock which was $3.00 a gallon. You just spray it on and it kills the moss almost instantly as the Pool Shock is concentrated bleach.

smitcat
Posts: 3067
Joined: Mon Nov 07, 2016 10:51 am

Re: Cleaning shingles (moss & mildew)

Post by smitcat » Sun Apr 14, 2019 6:36 am

Broken Man 1999 wrote:
Sat Apr 13, 2019 1:22 pm
jasg wrote:
Sat Apr 13, 2019 10:33 am
A family member used to live in your area and a zinc strip under the ridge shingles does wonders - but roofers hate to install them. They would rather your roof last for a shorter time...

Another approach is to put down a line of Arm & Hammer washing soda (sodium carbonate from the laundry aisle or from a pool supplier). As the rain washes it down, it creates a very basic environment that moss/mildew can't tolerate. Just do this every year along the ridge line and midway if you have a large roof. I do this annually to fight the moss in the PacNW.

I don't like pressure washing - around here they use an air compressor to blast off the moss. Less damage to shingles.
Interesting idea, using Arm & Hammer washing soda, first I've read about that. I'm not sure if that would work on my roof, as it is pretty steep. So far as pressure washing, that would be my absolute last choice, as I would fear damage by overzealous washers.

Sounds like the gentle application of some of the products mentioned should be tried first.

Thanks!

Broken Man 1999
Wet and forget will work very well but it will take a few weeks before you see results - it does work for months after application.
Bleach products will remove kill the growth but also corrode the roofing nails as well as the gutters and downspouts.
Active copper and zinc products will kill the growth if applied correctly but will also kill other plant growth on the ground when it gets there - and don't let it get to standing water please.

jasg
Posts: 93
Joined: Wed May 08, 2013 7:10 pm

Re: Cleaning shingles (moss & mildew)

Post by jasg » Sun Apr 14, 2019 11:13 am

The thing I like about sodium carbonate over other common solutions like laundry soap, zinc powders & Wet 'n Forget is the low environmental impact.

Sconie
Posts: 575
Joined: Sun Feb 07, 2010 10:23 am
Location: Arizona

Re: Cleaning shingles (moss & mildew)

Post by Sconie » Sun Apr 14, 2019 4:36 pm

I had the same problem on my roof up in northern Wisconsin and installed a line of lead strips beneath the ridge shingles, such that 2"-3" of the lead strip was exposed along the bottom edge of the ridge shingles. That cleared the shingle mold and mildew right up----not only that, but a supposed "20 year roof" ended up lasting 32 years. Zinc strips will work as well---probably copper too----although probably not as well as lead.
I know that you think you understand what you thought I said, but I'm not sure you realize that what I said is necessarily what I meant......

User avatar
PoultryMan
Posts: 22
Joined: Fri Feb 02, 2018 3:12 pm

Re: Cleaning shingles (moss & mildew)

Post by PoultryMan » Sun Apr 14, 2019 4:43 pm

I’ve used both and think spray and forget is a bit better. I mix it a little stronger than they say and make sure the roof is completely dry. 3-4 months you will be pleasantly surprised

LifeIsGood
Posts: 724
Joined: Mon Feb 11, 2008 8:43 pm
Location: Atlanta, GA

Re: Cleaning shingles (moss & mildew)

Post by LifeIsGood » Mon Apr 15, 2019 5:47 am

I need to undertake this project on my roof but the north side which has most of the shingle growth is probably 35 ft off the ground. Does anyone have any experience with a sprayer that has this kind of range?

Topic Author
Broken Man 1999
Posts: 2173
Joined: Wed Apr 08, 2015 11:31 am

Re: Cleaning shingles (moss & mildew)

Post by Broken Man 1999 » Mon Apr 15, 2019 3:27 pm

LifeIsGood wrote:
Mon Apr 15, 2019 5:47 am
I need to undertake this project on my roof but the north side which has most of the shingle growth is probably 35 ft off the ground. Does anyone have any experience with a sprayer that has this kind of range?
Even if you could get a stream that high, I think it would be difficult to control enough to be able to do a half-way decent job.

As an update, I received a bid for the job of $1500. The young man was so earnest telling me that he would be at my home for several hours. I am so proud I didn't burst out laughing when he gave me the bid.


Broken Man 1999
“If I cannot drink Bourbon and smoke cigars in Heaven than I shall not go. " -Mark Twain

Post Reply