Found possible mold during home inspection, owner says its not mold

Old 03-29-14, 06:17 AM
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Found possible mold during home inspection, owner says its not mold

Hello all,

I am a prospective homebuyer and found a house I really liked. I was as far as had an agreed price and signed contract, but during the home inspection found what appeared to be mold in the attic (along with a few other minor issues). Being that the house was already at the high end of my price range, I ended up killing the contract.

A few months have passed and the home owner hired a contractor to address and fix everything that came up during my home inspection. He examined the discoloration in the attic and claims that it is not mold.

The contractor says that the discoloration is the result of frost occasionally appearing in the attic and melting. He claims that the attic area is meant to be as cold as the outdoors, as the insulation is in the attic floor rafters. He also said its not unusual for frost to form on the underside of the plywood under certain conditions.

I guess this also raises the question of if what the contractor says is true, does this mean there's an insulation issue with the attic if condensation is building up there? For what its worth, the woman who lived there previously was constantly running an unvented standalone propane fireplace in the winter. I'm wondering if this could cause the condensation?

Below are a couple of pictures I have from my home inspection. They are small size and not so great quality, so I apologize in advance but its all I have.

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I realize its probably very difficult to tell, but do you think there could be any truth to what this contractor is saying? I've asked a few people and posted this on another message board and got wildly different answers, most people saying they wouldn't let it kill the deal, but had someone saying the entire roof down to the framing needs to be replaced. Any thoughts would be greatly appreciated
Old 03-29-14, 06:39 AM
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Welcome to the forums!

It is very common for frost to form in an attic as the contractor says. Warm air will infiltrate into the attic from the living space and that warm air will then condense on the under side of the roof, the coldest part of the attic. The ways to combat this is to stop air leaks to the attic, add more insulation, and more/better ventilation to the roof.

I would agree with the others that said it should not kill the deal if it truly is frost, and there are thousands of houses with exactly the same issue in the winter. The one who said the entire roof and framing needs to be replaced is on crack, or is looking for a job.
Old 03-29-14, 06:46 AM
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Its quite possible that it "could be" mold. Everything the guy said about frost is certainly possible. Even grass can get mold on it from the dew every morning. Ever seen the white dusty stuff on the leaves of some plants? That's mold. But you don't dig your lawn up because of a little mold... you just cut it off regularly. Some people have allergies, I understand that. But some people are a little paranoid too. Just the thought of something makes them sick. There is going to be some mold in a house of that age, because a house has to stand for years and endure some of the same climate conditions that your lawn does.

Being in the construction business myself, I would say that I have a pretty good idea of what's normal and what's not. Like the carpenter you mentioned, I agree that some frost is normal, and nothing in the pictures is surprising or a deal-breaker. If there is frost in an attic, there could be some mold. But anyone who says the sheathing needs to be replaced based on what can be seen in the pictures is really "out of touch". There are multiple ways of dealing with mold. Number one, realizing it's not a big deal. Number two, Treating it or Number three, treating it and encapsulating it. Neither of these mean that it will never come back again. An unvented furnace would put lots of moisture into the air which would make any frost problems worse.

Unless it's brand new, every house will have "some" mold somewhere. Anywhere there is cold air meeting warm air (condensation creates the wet condition, as in your attic) like behind baseboard... or inside some wall cavities, anywhere there was a minor leak of any type. Mold is not the devil that most people would like you to believe. The bigger problem is usually the source of the moisture- such as a leak. Mold is often just an indicator of a bigger problem- a moisture problem. Take care of that that the problem usually evaporates... literally.

Mold can be destructive, but not usually by itself. It's the combination of a leak (say a roof leak) and the mold (which feeds on the wood) that speeds the decay of the wood products. So yeah, you don't want mold, but the bigger issue is the moisture source. If you poked at the plywood and your poker went right through... well that's a problem. But if it just looks bad, that's not a problem. Well, maybe a cosmetic problem. LOL

There is mold everywhere, and mold spores are present in every inch of air we breathe. Mold also only grows in certain conditions. It has to have the right humidity (moisture in/on the wood) and it needs to have the right temperature (only certain types of mold can grow in the cold when the frost is present... it is more common form mold to grow in warm temperatures- in the narrow window of time where the frost has melted, the moisture content of the wood is still high, the temperatures in the attic are getting warm, but BEFORE the air naturally dries out the moisture in the wood). So if you imagine the mold growing like crazy all year round, that's not the case. If it was, every attic would be covered in mold. As it is, there may be some mold... but when one of the conditions is removed (usually the moisture) the mold goes dormant... until the next time the conditions are right for it to begin growing again.

The sheathing really only needs to be replaced if its structural integrity has been compromised, and from the tiny amount of mold that might be in the photos, I don't think that's the case.

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