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    Default Condensation on HVAC Ducts

    I'm currently working on half a dozen projects in a 70 year old house.

    Today, I was up in the attic space finishing off the installation of a bathroom light/vent combo, & decided to check on an issue I ran into when trying to lag a beam across the new opening for my bedroom closet. I used a 1/4" bit to pre-drill holes for the 3/8" lag bolts, & had done so previously with very good results. However, when tightening the lag bolts for this beam, they would go in about 95% of the way, but would not tighten up.

    Having finished the bathroom light/vent early, I decided to take a look to see if I could spot a problem in the attic that might cause the lags not to go all the way in. While digging out the blown-in insulation over the closet space, I noticed that some of the insulation was wet, not just damp, wet as in I could squeeze moisture out of it. Since it hasn't rained in 3 days & the roof is less than a year old, & after running my hand along the bottom of the duct, I'm 99% positive that the moisture is comming from the ductwork. The duct in this location was covered to the top of the duct with the blown-in insulation which appears to be either cotton or wool fiber. I also noticed that the floor joists & attic floor were damp from the condensation. Short of running the air conditioner less, is there anything I can do to reduce or eliminate the condensation?

    As for the lags, I don't see anything that would prevent them from being fully tightened, so I may just remove them & use 3/8" Grade 5 Hex head bolts & lock washers to secure the beam with.
    Last edited by chaosdsm; 10-12-2007 at 01:31 PM. Reason: clarification

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