3 sided bump out-frost on ceiling

[Chaz]

New construction, first winter and 3-sided bump out is dripping in many places on top of inside walls where ceiling meets (not fast, just condensation type build up and then drewling down wall). Also, one part has frost on ceiling. Blown in cellulose insulation. Any ideas? My guess is the insulators missed the top, but hard to see in attic.

Thanks

[danh]

If it's condensation, and not water leakage from the attic, then the top of the wall must be very cold, such as from settling to the point where the top of the wall is uninsulated. But shouldn't old, uninsulated houses suffer from this type of problem? So there must be another component: interior humidity. Old houses survive cold walls because they are too leaky to sustain interior humidity higher than 25% RH. So if your humidity is 55%, step 1 is drop that to 35%, and get the wall reinsulated when you can.

Alternatively, you could have ice damming. Ice damming can cause water to back up under the shingles, and leak through the roof deck onto your walls. Its an easy fix: air seal the attic floor, and improve attic ventilation.