Attic Ventilation and Decking stains


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Old 06-05-14, 08:37 AM
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Attic Ventilation and Decking stains

Just purchased a new home. The attic has a few problems with inadequate ventilation (need additional soffit and roof vents, bath vents not venting direct to exterior). The decking has some linear staining on the back as shown in pictures.

Should I be concerned about it potentially being mold? Doesn't seem consistent with images I've seen for attic mold, but I'd like to solicit some experienced feedback. Replies appreciated. Thanks!

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Old 06-05-14, 09:16 AM
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Welcome to the forums Erik!

Mold needs 3 things to grow, food source [the wood], heat and moisture. Take away any one of the 3 and the mold won't grow. Fixing the ventilation issues, most importantly routing the exhaust fans to the outside should fix any mold issues. I wouldn't worry none once the bath vents are piped to the outside.
 
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Old 06-05-14, 10:23 AM
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Is that staining isolated or evenly occurring throughout the attic?
 
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Old 06-05-14, 10:30 AM
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It's pretty evenly distributed.
 
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Old 06-05-14, 11:23 AM
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Not an expert on molds, but I would refer to that staining as "mildew". Below is a link comparing mold and mildew. The biggest concern I see with the staining is future buyers might interpret it as a problem. Options are to find a solution that removes the staining or document the corrections you are going to make, but at this stage I see no weakening of the plywood or risk of mold. Remember, I'm not a pro.

When you are ready to talk venting I can help.

Bud

Mildew vs Mold - Difference and Comparison | Diffen
 
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Old 06-05-14, 04:16 PM
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Did you get a look at it in the dead of winter? You surely would have noticed ice clusters at each nail.

Before you take any action with regard to staining, which may be mold, you need to address the issues that lead to excessive moisture in the attic

Although ventilation is certainly a critical element of moisture control don't be fooled into thinking that even surpassing recommended ventilation levels that you will totally avoid condensation. You need to address the Relative Humidity of the structure and how moisture is generated and how it is diminished. This would include an analysis of air movement through the structure as well as a determination of what vapor retarder you may need as opposed to what you have.

I would be concerned about the integrity of the plywood. Too much wetting at the nail penetrations tends to carry water into the core of the material and even though it is laid up with exterior grade glue, the water will soak the wood which in and of itself is not water resistant.

You can get a mold test kit or hire someone to verify mold. Certainly if you see little fuzziness appearing on the sheathing or framing you can be assured that is mold. Bear in mind that mold spores are everywhere and as previously mentioned you need to control any or all of the conditions that allow it to prosper. Usually, moisture is the condition most readily controlled.
 
 

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