# Black mold on underside of plywood in addition....



## tomwalla

I built an addition about 4 years ago on an existing old house. Where the addition was tied into the existing house, I had a water leak develop. I have since fixed the leak, but have had a real bad case of black mold develop on the underside of the plywood. It is not in every rafter bay but in the bays that it appears, it is well entrenched. I have plenty of ventilation in the attic with a gable vent, a ridge vent and 2 small vents on the side of the roof that has the bad mold. I should mention that the side of the roof with the mold has a very slight pitched shed type (2/12) roof coming off a 8/12 pitched roof. I don't have any bath fans that empty into the attic and have fairly good soffit venilation. I am assuming that the mold started when the roof was leaking and was so well developed that it didn't go away after i fixed the leak. What is the best way to get rid of the mold?


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## titanoman

Bleach.


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## Maintenance 6

If you've fixed the leak and everything is now dry, the mold has gone dormant. That doesn't mean dead. It will still emit particulates and spores. First get some plastic around the area, so that when you disturb it, it's not falling down into insulation and other parts of the building. Spray it down with a detergent solution. and scrub it off with a brush. Wear a respirator (N95 with P100 cartridges). After it has thoroughly dried, treat it with a fungicide. There are several out there. Quaternary amonias, Phenols and Bleach. Take your pick. They all kill mold. Bleach is cheapest and easiest to use. Whatever you pick, apply it with a garden sprayer. Let it completely dry. Apply a sealer to lock down any stray fragments. Kilz, Zinnser all make sealers. The bleach bashers will be along shortly to post links to all the "mold is gold" websites that tell you bleach won't kill mold, but that's BS. Don't fall for it. Just don't be inhaling a lot of bleach fumes.
Often, the water stains on plywood are not all mold, but just that, water stains.


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## Nailbags

A simple fix use Bleach to kill it. Now some things people think is black mold is tannin stains from the wood and nails from water. But just bleach it good let it dry well and your going to be ok.


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## Gmun396627

*Hospitals USE !!!*

9 parts water to 1 part bleach even kills the aids virus ! I use it on my molding then paint seal once it is dry ! Someone let me know if there is a better way

Geoerge


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## Nailbags

Gmun396627 said:


> 9 parts water to 1 part bleach even kills the aids virus ! I use it on my molding then paint seal once it is dry ! Someone let me know if there is a better way
> 
> Geoerge


As long as you can smell the bleach it is good. I like using 8:1 ratio that kills the hep B virus that one is harder to kill then HIV.


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## Maintenance 6

Mold isn't bulletproof. 10% bleach will not only kill it, but will destroy the glucan bonds of the mold's cell walls and disolve the protiens inside to the point where they are not even considered allergens.* Just make sure you are well ventilated. Aerosolized bleach can easily form some nasty chloroform compounds that you don't want to be breathing. 

* Actually concentrations as low as 2.8% have been shown to be effective with a 5 minute dwell time.

The AIDS virus is pretty fragile outside of a warm body. Common cold viruses are some of the toughest critters. That's one reason why they are so prolific.


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## Gary in WA

Usually the mold on plywood comes off easily because it is on the surface, as said. You may have difficulty with Doug-fir lumber (organic material) and bleach alone: http://ir.library.oregonstate.edu/x...ff.Forestry.AbilityBleachOther.pdf?sequence=1

Gary


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## jasin

Bleach should never be used to kill mold, even though it does kill mold, or at least according to Osha it does. Here's why: The problem with Using bleach to kill mold is its corrosive. It can mess up, because it's corrosive, the integrity of whatever the mold is on when its used to kill mold. Only plastics and Glass can bleach be used on without it being corrosive because those materials are inert. In residential homes though mold is typically on things that are not made of plastic or glass. Also, you can't use it straight up as it is an irritant. It will make your skin itch and even feel like its burning your skin. So to make it less of an irritant it has to be diluted with water which reduces its concentration and as a result, its overall effectiveness.


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## jasin

Many often remove mold without remedying the situation. Preventing mold from coming back in the future. And that's a very BIG mistake.


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## Maintenance 6

It's interesting reading. I would love to know more about their test methods, like how did they isolate their test samples. I've read a number of these studies, but some make me wonder how valuable they are, especially when they have unexplained anomalies in their samples. Also notable that on the most common strains; the ones you'll likely find first on building components (aspergillius, penecillium), bleach was as effective as anything else. 

Bleach should never ever be used straight for anything. And that is why OSHA has an interest. Some remediation companies were having workers use straight bleach as a fungicide which is dangerous to the workers health. Other than their mandate to protect workers, OSHA has no interest in killing mold. Pretty much the same with any EPA studies. Their mandate is to protect the environment from injurious chemicals and processes. Emitting chloroform compounds into the atmosphere is contrary to their mandate. 

There is no reason to use bleach on hard surfaces such as plastic or glass. Those materials can be cleaned just as effectively with dish soap and save the chloroforms. The primary things to remember when cleaning up molds is that you first need to control the moisture that caused the problem. Otherwise your are wasting time. Second, it is not reasonable to think that any fungicide is going to penetrate porous surfaces and kill everything. That is why sealing the surface after treatment is important to lock down those mold components that cannot be reached. Hyphae/mycellium may become so deeply embedded in some porous surfaces that topical application of fungicides will not reach them. Without moisture control and sealing, those components will regenerate into fresh mold colonies. That is why some building components, such as drywall should just be replaced. The cleaning and treating time/cost versus effectiveness don't make sense. People tend to worry about spores, but spores are everywhere and are impossible to control and are opportunistic meaning they can float around until they can cling to a surface. There they will wait until conditions are right before blooming into a full fledged mold colony. Very, very few mold spores ever have that opportunity inside a structure.

1. dry it 2. clean it. 3. treat it. 4. seal it


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## jasin

Maintenance 6 said:


> It's interesting reading. I would love to know more about their test methods, like how did they isolate their test samples. I've read a number of these studies, but some make me wonder how valuable they are, especially when they have unexplained anomalies in their samples. Also notable that on the most common strains; the ones you'll likely find first on building components (aspergillius, penecillium), bleach was as effective as anything else.
> 
> Bleach should never ever be used straight for anything. And that is why OSHA has an interest. Some remediation companies were having workers use straight bleach as a fungicide which is dangerous to the workers health. Other than their mandate to protect workers, OSHA has no interest in killing mold. Pretty much the same with any EPA studies. Their mandate is to protect the environment from injurious chemicals and processes. Emitting chloroform compounds into the atmosphere is contrary to their mandate.
> 
> There is no reason to use bleach on hard surfaces such as plastic or glass. Those materials can be cleaned just as effectively with dish soap and save the chloroforms. The primary things to remember when cleaning up molds is that you first need to control the moisture that caused the problem. Otherwise your are wasting time. Second, it is not reasonable to think that any fungicide is going to penetrate porous surfaces and kill everything. That is why sealing the surface after treatment is important to lock down those mold components that cannot be reached. Hyphae/mycellium may become so deeply embedded in some porous surfaces that topical application of fungicides will not reach them. Without moisture control and sealing, those components will regenerate into fresh mold colonies. That is why some building components, such as drywall should just be replaced. The cleaning and treating time/cost versus effectiveness don't make sense. People tend to worry about spores, but spores are everywhere and are impossible to control and are opportunistic meaning they can float around until they can cling to a surface. There they will wait until conditions are right before blooming into a full fledged mold colony. Very, very few mold spores ever have that opportunity inside a structure.
> 
> 1. dry it 2. clean it. 3. treat it. 4. seal it


Plastic shower curtains get mold on them very easily. But they are very thin, flexible, and pliable making them hard to scrub. You have to actually lay them flat to scrub them and still, even then, it does not go to well. Best way to clean them is not to scrub them but wash them in the washer machine with bleach. Also, I have heard its generally not recommend to scrub mold off as the mold spores can disperse, be breathed in, or stay on the object using to scrub it off.


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## Scottphys

Just posted this on another thread. Be careful with black mold.
Despite my dislike for the EPA, they do have good information about mold remediation. Check this out before proceeding and good luck!

http://iaq.supportportal.com/ics/support/kbAnswer.asp?deptID=23007&task=knowledge&questionID=21163


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## jasin

Scottphys said:


> Despite my dislike for the EPA


:laughing:


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## Maintenance 6

The mold on shower curtains is living on soap scum. Soap is high in fatty acids which makes good mold food. When spores are dry they are easily dispersed. If you wet them before you scrub, it's not an issue.

As far as the EPA, keep in mind that they are not an authority on killing mold. Their job is protecting the environment.

There is a ton of mis-information on the interrnet about mold and health effects. Most is hype from "Magic Mold Potion" sellers trying to pitch some product that is basically a batch of chemicals you can find under your sink.


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## Nailbags

Every home built has mold in it period. Ever frame up a house an it rained and got the wood wet? Well guess what that house now has mold in it. people over react to mold to much.


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## Scottphys

Maintenance 6 said:


> As far as the EPA, keep in mind that they are not an authority on killing mold. Their job is protecting the environment.


IMO they're not much of an authority on anything. Point well made Maintenance 6. 
Regardless, I've found their mold info helpful.


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## rusty baker

Maintenance 6 said:


> The mold on shower curtains is living on soap scum. Soap is high in fatty acids which makes good mold food. When spores are dry they are easily dispersed. If you wet them before you scrub, it's not an issue.
> 
> As far as the EPA, keep in mind that they are not an authority on killing mold. Their job is protecting the environment.
> 
> There is a ton of mis-information on the interrnet about mold and health effects. Most is hype from "Magic Mold Potion" sellers trying to pitch some product that is basically a batch of chemicals you can find under your sink.


 Just like asbestos and lead danger. Overblown.


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## jasin

Nailbags said:


> Every home built has mold in it period.


This is totally false!


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## Nailbags

jasin said:


> This is totally false!


If your going to quote me you better do it in full context and with formidable information. because During the farming job before it is dried in it will rain the wood will get wet. And it will cause mold to grow. Also all wood was a living organism and once it was felled it will start to rot Doug Fir and Hemlock have fungus naturally in the wood fibers that when wet will start the mold to activate. the sap in the wood has sugars in it that help break down the wood when the molds hit it. Would you like more scientific information or are you just going to miss quote me? Now unless you live in the dessert and have zero chances of precipitation then all the home built will have some form of mold in them. I have built homes in the driving rain and having to drill holes in the sub floor to let the water drain out. And I have gone back ad have seen the mold stains in the studs. It is not a problem just people over react to the "mold" it there and there is nothing to worry about.


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## Scottphys

I've read the same thing; that mold is everywhere. Even if it didn't rain on the construction, mold spores float around outside and could come inside. That's why when you do mold tests, they prefer an indoor sample and an outdoor sample as well. 

The key to keep mold growth "at bay" is to maintain less than 55% relative humidity where mold won't be able to survive.

Like everything Preventative Maintenance is important.


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## Gary in WA

I've been researching bleach/mold. A few points: 

Bleach will kill surface mold, but *not ingrain mold in lumber* because it is *organic which inactivates bleach*. http://www.toxic-black-mold-info.com/disinfectant.htm

http://www.spore-tech.com/viewCategory.asp?idCategory=78

Has anyone found any articles to show otherwise? I,d be interested in finding more information on the high-lighted comments above, Thanks, Gary


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## jasin

Scottphys said:


> The key to keep mold growth "at bay" is to maintain less than 55% relative humidity where mold won't be able to survive.
> 
> Like everything Preventative Maintenance is important.


This is Correct.


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## Maintenance 6

The info in the toxic black mold info link is pretty accurate, but you need to understand what "inactivated by organic matter" means. It means that as the compound does it's job it becomes weaker until it is ineffective. It has little residual "killing power". Would you really want a chemical residue to remain active after it's job is complete? I'm really surprised that alcohol is on the list, since it is never used as a remediation product. In fact alcohol is a by-product of the metabolism of more than one mold specie.

The Spore Tech site is another of the "Mold is Gold" sites out there. A grain of truth, but a lot of BS in between. Example: "OSHA is the first federal agency to announce a departure from the use of chlorine bleach in mold remediation." What does OSHA know or care about killing mold? Their interest is in NOT killing workers. (See previous post). 

Here are some links from more reputable sources

http://accessscience.com/studycenter.aspx?main=5&questionID=4918

http://www.jacionline.org/article/S0091-6749(04)00083-1/abstract


Let me also add that unless you are totally familiar with them, you should NEVER use *Glutaraldehydes for remediation.*

If one reads the fine print on the mold remediation products sold, you'll find that all of them include disclaimers about deep seated mold in porous materials and that they offer no guarentees about their effectiveness. That includes some of the best fungicides out there.

Is bleach the absolute best product out there? No. Do I use it on remediation jobs? Somtimes. Depending on conditions. In highly sensitive places? Yes. It leaves very little in long term chemical residuals.

It is easy to use. Readily available and as effective as most other products. Everybody has a bottle in their laundry room. It is also easy to mis-use. Never exceed 10%.


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## Maintenance 6

Nailbags said:


> Every home built has mold in it period. Ever frame up a house an it rained and got the wood wet? Well guess what that house now has mold in it. people over react to mold to much.


I totally agree with that. If you know where to look, you will find mold. Practically all mold on framing goes dormant after the structure is dried in and never resurfaces as a problem. There is also a ton of misleading information out there about "toxic mold". There is also a lot of misconceptions about mold spores. Mold spores are everywhere. Unless you are living in a clean room, the last breath you took included more than a few. I once saw a worker screw up an air clearance sample when he ate his lunch on a jobsite. He sprinkled ranch dressing on a salad near an air pump and drove the spore counts up. Want a real dose of spores, open a loaf of moldy bread in your kitchen. And bread molds produce some of the nastiest by-products. I never once heard of anyone who died from breathing moldy bread. That's not to say that it's safe to be exposed to overwhelming spore loads or mycotoxins, or to say that some molds don't produce really nasty things. After all, Anthrax is a mold by-product. Common molds in buildings don't make anything close to that.


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## jasin

Maintenance 6 said:


> I totally agree with that. If you know where to look, you will find mold. Practically all mold on framing goes dormant after the structure is dried in and never resurfaces as a problem. There is also a ton of misleading information out there about "toxic mold". There is also a lot of misconceptions about mold spores. Mold spores are everywhere. Unless you are living in a clean room, the last breath you took included more than a few. I once saw a worker screw up an air clearance sample when he ate his lunch on a jobsite. He sprinkled ranch dressing on a salad near an air pump and drove the spore counts up. Want a real dose of spores, open a loaf of moldy bread in your kitchen. And bread molds produce some of the nastiest by-products. I never once heard of anyone who died from breathing moldy bread. That's not to say that it's safe to be exposed to overwhelming spore loads or mycotoxins, or to say that some molds don't produce really nasty things. After all, Anthrax is a mold by-product. Common molds in buildings don't make anything close to that.


There is no reason a new house should have mold in it unless its built wrong. The fact that New products off the shelf do not have mold on them is proof of that. Lowes, home depot, etc. cannot purposely sell stuff with mold on it. It would be a liability and they would lose business.


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## Maintenance 6

I can pretty much guaranty that I could find mold somewhere in practically any house. It's a fact of life. Most of it can be there for years and never cause any problem, but it's still there. The first place I would look is under the kitchen sink, then in the vanity and after that, the laundry room. And that's not taking into consideration anything that happened during construction and left some dormant colonies however small.


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## jasin

Maintenance 6 said:


> The info in the toxic black mold info link is pretty accurate, but you need to understand what "inactivated by organic matter" means. It means that as the compound does it's job it becomes weaker until it is ineffective. It has little residual "killing power". Would you really want a chemical residue to remain active after it's job is complete? I'm really surprised that alcohol is on the list, since it is never used as a remediation product. In fact alcohol is a by-product of the metabolism of more than one mold specie.
> 
> The Spore Tech site is another of the "Mold is Gold" sites out there. A grain of truth, but a lot of BS in between. Example: "OSHA is the first federal agency to announce a departure from the use of chlorine bleach in mold remediation." What does OSHA know or care about killing mold? Their interest is in NOT killing workers. (See previous post).
> 
> Here are some links from more reputable sources
> 
> http://accessscience.com/studycenter.aspx?main=5&questionID=4918
> 
> http://www.jacionline.org/article/S0091-6749(04)00083-1/abstract
> 
> 
> Let me also add that unless you are totally familiar with them, you should NEVER use *Glutaraldehydes for remediation.*
> 
> If one reads the fine print on the mold remediation products sold, you'll find that all of them include disclaimers about deep seated mold in porous materials and that they offer no guarentees about their effectiveness. That includes some of the best fungicides out there.
> 
> Is bleach the absolute best product out there? No. Do I use it on remediation jobs? Somtimes. Depending on conditions. In highly sensitive places? Yes. It leaves very little in long term chemical residuals.
> 
> It is easy to use. Readily available and as effective as most other products. Everybody has a bottle in their laundry room. It is also easy to mis-use. Never exceed 10%.


This is good info :thumbup:


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## jasin

Maintenance 6 said:


> I can pretty much guaranty that I could find mold somewhere in practically any house. It's a fact of life. Most of it can be there for years and never cause any problem, but it's still there. The first place I would look is under the kitchen sink, then in the vanity and after that, the laundry room. And that's not taking into consideration anything that happened during construction and left some dormant colonies however small.


I am glad I do not live where you work because the contractor who's building and/or remolding these houses is clearly not doing it right.


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