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A recent remodel raised the ceiling in the great room. An LVL beam was installed under the ridge beam to carry the load and 2X nailers were installed running from the LVL beam to the top plate. The contractor then installed kraft paper backed fiberglass insulation between the 2X nailers. 1×6 T&G knotty pine then nailed over the insulation. No vapor barrier or sheetrock between the pine boards and fiberglass. Continuous ridge vent and soffit vent are also present.
Problem is that moisture is apparently condensing on the cold roof sheathing and dripping into the room. One suggestion to correct this is to install foil faced rigid foam board with all of the seams taped over the existing wood ceiling and install new wood over the rigid foam in an effort to stop warm moist air from reaching the cold sheathing. Does this sound like a viable fix? The contractor who did the original work says he is willing to do the labor but not pay for any new materials. I think he should do the whole ball of wax, since if he had done this correctly from the start, I wouldn’t even be writing to this forum. Thanks for any info.
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Marc- I'm expecting you'll get more experienced answers here, but I'll give my 2 cents. I would have added a plastic vapor barrier over the FG insulation. Also, code often (always?) requires fire-rated backing on a ceiling or wall like this. When insulation is installed between rafters, up next to roof, there must be provision above the insul. to allow air movement from soffit to ridge- sounds like air passage has been restricted by the insul.. There are products made as a baffle to create this continuous air flow. It's good that you have the vents, but they won't do much good if they block the flow of air. - Ken
*Marc, I'm not sure I'd be so quick to judge the remodeler. Sounds as if the old ceiling was not insulated properly. Wonder what size rafters and r-factor you had there?Also if there if the isulation is fg, and the ventilated air is flowing over it, it's effectiveness is greatly reduced. A continuous vapor barrier above the t&g may have mitigated the infiltration, but would have been compromised by the many nails used to install pine boards.You might want to consider blocking the ventilation either at the ridge, soffits or both if practical as the warm moist air would probably not migrate to the insulated space if there was not an outlet for it.The whole system is engineered wrong, not just what the remodeler added, which I assume he did at your direction or at least approval.What, in your opinion, is the roof ventilation doing anyhow? I'm curious.
*Marc,Ditto on Ken's message. The vaulted ceilings that I have seen have all had a space between the insulation and the roof decking so that air could circulate. None of them had a condensation problem. I've seen both plain insulation and insulation with a vapor barrier over it used also. I don't know if one holds any particular advantage over another. I've heard so many arguments on both sides of the coin that it gets confusing at best.I am getting a little concerned about the trend to buttoning up a house so tight that make-up air systems have to be installed to make them habitable. Recently I was in a new house (approximately a $500,000 market valuation) that had to have such a system retrofitted because it was so tight. They laughed about it, but after seeing wraps like Tyvek take a hit, perhaps we have gone too far in this direction, but that's another issue.Good luck.Cliff.