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Mold on attic gable vent blockers after ridge vent installed

Mold on attic gable vent blockers after ridge vent installed


  #1  
Old 08-11-06, 11:32 AM
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Mold on attic gable vent blockers after ridge vent installed

I had a new roof installed 15 months ago. Because I switched to a ridge vent, I blocked my 2 attic gable vents with plywood nailed up over the vents from the inside. The 2 pieces of plywood are now covered in spots of black/grey mold. Any ideas on what could be causing this?
- plywood not airtight (do I need to caulk around it)?
- use painted outdoor wood?
- put housewrap on the outside side of the plywood?
- plywood already contaminated?

I don't think it's a general attic moisture/vent problem, because there are no other signs of mold or moisture on the roof sheathing or trusses, or any wood in the attic. Only the plywood blocking the vents. Both bathrooms and the kitchen fans are vented up through roof vents and were replaced when I replaced the roof. My roofer swears I have enough soffit vents for adequate ventilation. Should I drill out some more soffit vents, anyway?

Thanks!
 
  #2  
Old 08-11-06, 01:13 PM
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Wink

Id sure open up the gable vents and let them open . The more vents you have up there the better off you are. Think of the roof is there to just keep the rain and snow off the R 30 insulation you should have there.

ED
 
  #3  
Old 08-13-06, 08:18 AM
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Blocking gable vents after ridge vent installed

The gable vents are supposed to be blocked after a new ridge vent installation because they could short circuit the airflow. Air is supposed to flow in through the soffit vents, then along the roof surface, and out the ridge vent.

So if the mold is from a general attic moisture problem or lack of ventilation, then I'm supposed to drill more soffit vents. However, there is no mold anywhere else in the attic, plus my roofer swears I have way more than enough soffit vents. Both of those indicate that I have enough venting and the mold is coming from some other moisture source.

Any ideas? Thanks.
 
  #4  
Old 08-13-06, 08:25 AM
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Could open the gables and see what happens??

You should have 1 sq ft vent for every 150 sq ft of attic 1/2 in 1/2 out. For a vent fan you need .
sq ft of attic X 0.7===CFM of fan.

ED
 
 

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