White substance on attic insulation


There are many possible ways for moisture intrusion to enter the attic, but there is one that will baffle the most experienced professional roofer?

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You got me. What is it??

Answer to the question, How did the insulation get wet?

OK, Not to say this is how the moisture entered the attic in your pic’s but the moisture pattern in the insulation fits the pattern of slow-melting snow. Windswept snow can blow up through soffit vents and through gable vents leaving snowdrifts in the attic You can google snow in the attic, and there is a tread on the forum titled snow in the attic, Check it out.

I have seen this phenomenon several times the snow in this pic shows snow clinging to the truss web and snow on top of the insulation.


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I’ve seen this as well! :grinning:

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It is more common then you think, but it melts before anybody sees it, when it melts and stains the ceiling roofers think it is from ice damming, and they repair or replace the roofing. and then the process starts all over the next time you get wind swept dry powder snow. :grinning:

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Yes, I’ve seen snow in the attic a few times. The snow in the photo I posted above, was directly below the ridge.

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I have blocked off soffit vents in problem areas for a quick fix, there are other methods but went for the quick fix it is usually just a small section of venting that needs to be sealed. It will probably be called out by a HI someday HAHA.

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That is what I said.

You did not explain your answer, I took it as a clue and nobody caught on to it, O well, I should have said nothing and let the thread die.

You are good, but I believe I am also …LOL!
Love you Brother! Yep!