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mold on vaulted ceiling


AHI in AR
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I got a call from an acquaintance yesterday to look at mold growing on a vaulted ceiling in his five-year-old home. It's fully vaulted; there is absolutely no attic space above it. The roof was replaced this spring due to hail damage, and recently the owners noted mold. The house is equipped with continuous soffitt vents, and a continuous ridge vent. The recessed lights in the ceiling were an enclosed sealed type so I couldn't see the insulation or verify the presence of baffles. The mold was in various spots on both sides of the ceiling in no discernible pattern. I'm thinking moisture trapped in the insulation. The only conclusion I can come to is that there are either no baffles installed -- or they are somehow not functioning properly -- or there is a defect with the ridge vent installation. There are no damaged drywall joints or stains indicating an actual leak. Besides, it would be pretty odd to have it leaking on both sides when the roof is only a few months old.

I recommended that he have a roofer remove the ridge vent to check for properly sized slots under there as well as to try to verify whether baffles were indeed installed. I think he could probably slip his fingers in there and check for wet insulation also. Although if there's any venting whatsoever I can't imagine damp insulation at the ridge. Of course, I have also seen boneheaded roofers run the felt right up over the cutouts for the continuous ridge vent, rendering it useless. For the record, I didn't recognize the brand of ridge vent but it is not one of the types with a baffle on the bottom edge.

Anybody have any other ideas as to possible causes?

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For the record, the ridge vent was changed also. It could be underperforming whereas the original product didn't. And on insurance jobs around here it's routine to change out the felt also, so the roofers may have covered the vent openings.

Really...there was no sign of leaks. As I said, no stains or loose tape. I did look at the roof from the gutter line, and nothing looked amiss. (too steep to walk)

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The mold was in various spots on both sides of the ceiling in no discernible pattern. I'm thinking moisture trapped in the insulation. The only conclusion I can come to is that there are either no baffles installed -- or they are somehow not functioning properly -- or there is a defect with the ridge vent installation. There are no damaged drywall joints or stains indicating an actual leak. Besides, it would be pretty odd to have it leaking on both sides when the roof is only a few months old.
I think you're saying that the mold is visible/growing on the "living space" side of the drywall. If it was from what you suggest, the drywall, insulation and framing behind would likely be a saturated mess.

My guess would be that moisture inside the home is condensing on the cold "vaulted" ceiling. I would suspect an insulation problem and this has been developing for some time - they're just now clearly noticing it. I'd be suggesting a method to measure moisture levels well above the finished surface, to determine if I was right or wrong.

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I think you're saying that the mold is visible/growing on the "living space" side of the drywall. If it was from what you suggest, the drywall, insulation and framing behind would likely be a saturated mess.

My guess would be that moisture inside the home is condensing on the cold "vaulted" ceiling. I would suspect an insulation problem and this has been developing for some time - they're just now clearly noticing it. I'd be suggesting a method to measure moisture levels well above the finished surface, to determine if I was right or wrong.

How does the top of that vault ceiling get cold in August? Or are you suggesting that the condition was there last winter?

Marc

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Something else changed besides the roof cover. Maybe the A/C is short cycling, or the bathroom exhast fans are dirty and can't push the moisture outside, maybe they just aren't diligent about using them any more, or the filter is clogged on the air exchanger. Or maybe the stains have been there all along and they notice them now because they are paying attention to that ceiling because of the hail damage. People are funny like that.

The ridge vent is plausable, but I'd run around and check a few fans/filters too.

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I do think the condition has been around for a while; it's either just now showing up OR being noticed. Owner said his S.O. was normally very observant and they were pretty sure the mold wasn't there previously. Who knows.

I went out as a favor after a call from a guy who used to be a friend but whom I hadn't heard from in 25 years after he moved away. Anyway, he simply said he had a roof leak w/o mentioning mold. When I went out there, I didn't even take tools other than a ladder and flashlight. I guess I need to go back with the SM and check for moisture.

Tom--it's a vaulted ceiling over a family room. No attic space for anything to vent into.

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