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Discussion Starter · #1 ·
Hopefully some of you guys can give me some direction with this one. Buddy on mine has a house that was built in 1991 which he has been living in for about 6-7 years. About 2 years ago there was an issue with mold on the sheathing and rafters so he got a settlement from the insurance company and the roof was completely torn off including the structure and replaced with new 2x8 an lvl ridge and 5/8 OSB. I know of the contractor that did the work and he usually does decent work. While I have not verified yet my friend said that they ice shielded the entire roof when they did this work. They also added ridge vent and there is existing vinyl soffit vent and they left the 2 12 x 16 gable vents as well.

So this past weekend he goes into the attic to get the Xmas decorations and sure enough there are small puddles on the stuff in the attic and the OSB is visible wet and turning black again.

I stopped by and took a look tonight and it doesn't look good. The OSB is wet over a very large area so its not a leak in the roof but I didn't walk the roof yet. The ridge went looks correct and while there are no baffles there is clearance between the fiberglass and roof deck at the eves. So there has to be a source for this moisture. I found an broken HVAC trunk that sends heat to the 2 bathrooms that is definetly contributing to the issue but with all that venting up there I can believe that its the sole cause. The 2 baths don't have any fans either so I don't like that at all.

So step 1 is to fix the HVAC. The insulation isn't great but its far from awful so sweet can clean that up as well. I turned down the humidifier on the furnace as well and we have the attic fan running.

I guess I'm just questioning if something as small as the broke. Duct could cause this so quickly?? Should we add more vents?? I'm not the biggest fan of ridge vent but with the additional gable vents I would think this was adequate for a 30 x 25 x 6 foot attic. Is the ice shield to blame for creating this problem due to the fact that the deck can't breath??
 

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Where is the house located? Blowing hot air into a cold attic can most definitely cause a major issue. No bath fan ventilation can also contribute. Don't mix gable vents and ridge vent or you can pull snow and rain through the gable vent Into the attic.
 

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Fix the obvious things: broken duct; get fans in the the bathrooms. When the furnace fan turns off and stops pumping humidified air into the attic through the broken duct, then the humid air from the baths heads right up through the same duct and releases into the attic. I can see those two things making a giant mess.
 

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Discussion Starter · #4 ·
Located on long island so not extreme winters but cold enough. I don't see any signs of water and snow being pulled in.
 

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I've been in attics in winter were condensation is frozen on the sheathing and the roofing nails have frozen icicles on them.
He must be loosing heat and like said start at repairing the hvac and getting bath fans. Also look to see if he has any recessed cans and if they are ic rated. Is the attic hatch sealed also.

Is the problem on the north side of the attic and is there any large trees forming a canopy, like pines, and preventing the sunlight from hitting the house?
 

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Air seal the ceiling and make sure nothing from the house is venting into the attic. All that moisture is coming from somewhere.:thumbsup:
 

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The condensation is surely from the interior living space.

Many things can contribute to moisture migrating to the attic.

People with humidifiers on forced air HVAC run a higher risk of moisture problems. See if this is the case and have the humidifier setting lowered if possible.

Bathrooms should be vented to the outside. Even if the fans don't blow into the attic, the moisture has to go somewhere. Some will permeate into the attic space.

Recessed ceiling lights are notorious leakers of moisture laden air.

Different family situations will produce different moisture characteristics. A family of 5 taking showers every day and the cooking to provide for them will produce a lot of moisture.

Passive ventilation may not adequately remove the moisture. A power vent running on both a humidistat and a thermostat can be an effective fixture for some applications.
 
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