# Moss on asbestos shingles



## crescere (Aug 17, 2012)

I have green moss growing on my asbestos shingles. The house was built in the 1930s. What is the best way to get this stuff off without damaging the shingles? I tried a product from the Bayer Company for moss, and it turned it brown, but it still will not come off after I used a broom. I cannot actually step on the roof or I will break the shingles. 
Also is there any coating or treatment I can or should use to treat the asbestos shingles to prolong their life?


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## joecaption (Nov 30, 2011)

If the roofs in that bad a shape I'd leave the moss on the roof. It's not doing the roof any harm.
Round Up will also kill the moss.


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## crescere (Aug 17, 2012)

The roof seems okay in that there are no leaks. The moss is caused by a large amount of trees in this neighborhood. I trimmed what is on my property, but this will be a continuing problem here. I have read that moss will grow, and damage the shingles by lifting them up. Plus it does not look good on an otherwise nice stately house. 

Will roundup damage the shingles?


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## joecaption (Nov 30, 2011)

Wet moss covered asbestos shingles are going to be as slippery as whale snot. No way I'd want to be up on that roof cleaning it.
There's companys that do nothing but clean roofs, I'd be checking into that.


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## crescere (Aug 17, 2012)

joecaption said:


> There's companys that do nothing but clean roofs, I'd be checking into that.


 
I would not let anyone walk on those shingles. I just want a reliable chemical that will not harm the shingles and kill the moss so I can brush it off with a long handle broom while I stand on a ladder.


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## jagans (Oct 21, 2012)

Those are probably the original roof shingles and they are asbestos. That is a real tribute to AB as a building material. Frankly Id leave the moss alone, thats probably keeping the water out, and it is a "green" encapsulant. Kill the moss and broom it, and you could make it friable. Id leave the moss and tear it off as a unit. Frankly the old felt under the AB is probably the only thing keeping you and the weather from coming together at this point.


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## crescere (Aug 17, 2012)

jagans said:


> Kill the moss and broom it, and you could make it friable. Id leave the moss and tear it off as a unit. Frankly the old felt under the AB is probably the only thing keeping you and the weather from coming together at this point.


The entire roof is not covered in moss. Only the part near trees has moss on it. I was hoping someone knew of a chemical I could use that actually worked, but did not harm the shingle. What about bleach?


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## Dave Sal (Dec 20, 2012)

I haven't used this myself but Bayer products seem to work well, even if they may take awhile.


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## OldNBroken (Jun 11, 2008)

crescere said:


> I tried a product from the Bayer Company for moss, and it turned it brown, but it still will not come off after I used a broom.


:whistling2: :whistling2: :whistling2:

Don't know what to tell you to use as moss and algae are regional issues but I can tell you do NOT use bleach.


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## jagans (Oct 21, 2012)

Can you post some pictures of this roof? Id really like to see it if it is 77 YO and holdin. Im sure ONB would be interested too.


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## paintdrying (Jul 13, 2012)

same problem on friends house three companies cam out and told him he needed a new roof. The fourth guy sprayed something on the roof and the moss turned brown. The guy told me moss is difficult to remove and that my friend is just throwing his money away.


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## crescere (Aug 17, 2012)

Dave Sal said:


> I haven't used this myself but Bayer products seem to work well, even if they may take awhile.


 
I did use that, and it turned the moss brown, but the moss did not come off.


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## crescere (Aug 17, 2012)

OldNBroken said:


> :whistling2: :whistling2: :whistling2:
> 
> Don't know what to tell you to use as moss and algae are regional issues but I can tell you do NOT use bleach.


Why? What is is the bleach will do to the shingles?


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## OldNBroken (Jun 11, 2008)

Chlorine is a corrosive agent. Granted it is on the milder side, but still corrosive. Also it will not get to the "root" of your problem. Bleach is good for killing and neutralizing surface organics but little else.


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## crescere (Aug 17, 2012)

OldNBroken said:


> Chlorine is a corrosive agent. Granted it is on the milder side, but still corrosive. Also it will not get to the "root" of your problem. Bleach is good for killing and neutralizing surface organics but little else.


 
The root of the problem would be the trees, but they are not on my property so cutting them down is not possible. I am concerned that as the moss grows it will push up the shingles that are now not leaking. I did a Google search and there is a company that sells a product called D/2 Biological Solution which is supposed to be gentle on surfaces. I welcome any other suggestions.


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## mgp roofing (Aug 15, 2011)

Leave the moss alone--decades of weathering will have loosened asbestos fibres on the surface, which the moss and algae are holding in place. Remove the moss, and those loose fibres can get airborne


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## crescere (Aug 17, 2012)

mgp roofing said:


> Leave the moss alone--decades of weathering will have loosened asbestos fibres on the surface, which the moss and algae are holding in place. Remove the moss, and those loose fibres can get airborne


 
From what I have read this asbestos scare is like the mold paranoia. The fear generated makes lawyers and abatement companies rich. If I do the job I will wet the shingles and use a respirator, but I doubt doing one job one time will hurt anyone. If the moss will grow and cause the shingles to lift I certainly do want to get it off. If it is just cosmetic I do not care. 

Do you know of any chemical I can spray on the shingles to extend their life?


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## OldNBroken (Jun 11, 2008)

I've never heard of moss being able to lift the shingles but I guess it is possible. Have you seen it?

Asbestos health hazards are not just paranoia but you are correct that removing those shingles is not a major challenge as I stated earlier. I do recommend wearing a respirator but I would not advise wetting the shingles. Unnecessary pain in the buttox as well as a possible safety hazard.


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## jagans (Oct 21, 2012)

You want to "extend the life" of shingles that were installed 80 years ago? You should carefully remove them and put them in the Smithsonian. God knows they don't owe you anything.

As far as AB goes, when you remove them wet them down with a 3 to 1 mixture of water/glycol (antifreeze) mixture, then wear a good repirator.

Were I you, I would get them off while they are still in relatively good shape.

As I said before, it is probable that the felt below the shingles has been keeping the water out for the last few years.

If I recall correctly, individual rolls of #30 felt were installed between each course of asbestos shingles. Let us know if this is the case, will you?

_*EDIT: Yeah ONB might well be correct re wetting, glycol will make this roof as slippery as trying to grab an eel out of a bucket of snot.*_


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## crescere (Aug 17, 2012)

jagans said:


> Were I you, I would get them off while they are still in relatively good shape.


The house was built in the 30s, but I do not know when these shingles were put on. I just do not see any reason to remove shingles when the roof is not leaking.


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## dabeast (Apr 2, 2013)

The roof could be leaking you might just not see it.

I had my roof leak one time and it ran down the wall to the basement where there was a floor drain so I never saw any visible damage until I did a remodel.

This may not be your case but I would get a new roof if it is that old.


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## OldNBroken (Jun 11, 2008)

He's only concerned about moss removal. Why is everyone telling him to replace his roof?
It is not uncommon for these shingles to last this long. As I said earlier they are durable as hell . Their main enemy is impact damage. 
There are many many old craftsman homes around here from that era and the asbestos shingles on them are still in great shape.


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## jagans (Oct 21, 2012)

OldNBroken said:


> He's only concerned about moss removal. Why is everyone telling him to replace his roof?
> It is not uncommon for these shingles to last this long. As I said earlier they are durable as hell . Their main enemy is impact damage.
> There are many many old craftsman homes around here from that era and the asbestos shingles on them are still in great shape.


Yeah, you may be right ONB. I just assumed they were the old AB shingles made by Manville back in the 30's and 40's, there have been a few others produced much more recently than that, like Suprador Super Slate, (Now defunct from lawsuits) and I know that Eternit made one too. So much for assuming.

Pictures sure would have helped in this case.


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## OldNBroken (Jun 11, 2008)

jagans said:


> Pictures sure would have helped in this case.


Yes they would. I tell ya though I see many of those shingles still on houses around here and they are holding up extremely well. Tore one off last year that were in excellent shape. The owner just built a new shop/garage and wanted everything to match so we removed them and installed new grand canyon on everything.


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## mgp roofing (Aug 15, 2011)

OldNBroken said:


> Yes they would. I tell ya though I see many of those shingles still on houses around here and they are holding up extremely well. Tore one off last year that were in excellent shape. The owner just built a new shop/garage and wanted everything to match so we removed them and installed new grand canyon on everything.


I still see quite a few of these roofs here, too. Mostly the corrugated sheets, but some shingles too. They last well unless damaged by impact or being walked on. My advice is if it isn't leaking, leave it alone. In saying that, I have seen them cleaned by spraying with moss killer then once the moss is dead and starting to come loose, the roof is washed with low pressure water taking care to collect the wastewater and debris which must be disposed of at a licensed AB disposal site. Then the roof is either sealed with a silicone based water repellent, or a specially designed paint coating. 

Failure of the corrugated sheet roofs is usually because the fasteners rust out--I have stripped roofs from the 20s and 30s where the sheets have been sound apart from having loose AB fibre on the surface, but hardly anything left of the fasteners, and plenty of rot in the battens/purlins from water getting past the fasteners.

James Hardie were the main manufacturer here, there were a couple of small mfgr's as well, the names escape me now.


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## jagans (Oct 21, 2012)

There is no doubt about it. Asbestos is without question the best, and most maligned building materials that has ever existed, and one that is almost universally misunderstood.

A couple of years ago, I sent a long letter to one of our so called conservative senators from MD regarding the incredible waste of taxpayers money that was going on regarding asbestos abatement with regard to built up roofing systems on schools and other institutions, and how the state could save a lot of money with regard to this issue. I received a form letter from an aide thanking me for my letter, and would I like to contribute 50-100- or 1000 to the senators reelection?

A big change was made in OSHA several years ago in how low slope roofing containing AB was handled. In their infinite wisdom, they ruled that if there was only AB in the flashing, then it was to be considered incidental, and of no consequence.

Now anybody that knows anything about the older built up roofs knows that generally speaking, (Not always now) AB 20 was used in flashings only due to its relatively high cost, compared to organic (cellulose based) felts. They also know that when AB was used in the field sheets it remained encapsulated in asphalt, and was usually flood coated with asphalt and gravel, and therefore posed no hazard.

Now since the AB was used as a flashing material for base flashings, the sun would oxidize the asphalt over time, and since the AB was so durable it was the only thing left after about 35 years. Eventually it broke down and became friable, presenting a hazard.

So the bottom line is that where AB actually became a hazard, they ruled it as incidential, and where it was no hazard at all they ruled it as hazardous, and said it must be abated.

I guess it was the same guys that ruled on Agent Orange. The stuff that killed a lot of my friends after getting dosed with it in Nam.


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