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Moisture where ceiling and walls meet on exterior walls

Patrick Conry | Posted in Webinar Follow-up Q&A on

Hi I recently read a article on here talking about my exact problem and that someone had did a study to fix it , I was having trouble completely understanding if the three things they did worked at all? One was insatlling 6 inch insulated crown moulding in the interior of the house. I can’t find it for sale anywhere and I read another article that some guy used 6 inch mdf crown moulding and drilled holes in it and sprayed great stuff into it but he never said if that fixed his issue or not. Also my entire soffit is ventilated I was wondering if I closed off some or all during the winter if that would help with my problem. I’ve added insulation 2 times to my attic and tore down the soffit and installed 2 inch foam insulation on the osb sheating above the soffit, I run dehumidifiers in the winter both those seemed to help a lil but I still see in bubbling up the ceiling paint and running down the walls, please help Any info would be great. Thank u

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  1. GBA Editor
    Martin Holladay | | #1

    Here are links to two previous threads on this topic:

    Interior insulated cornice for use under low-heel roof trusses?

    Weird top-plate area idea

    As those two threads make clear (and as my original article in Energy Design Update also made clear), the idea of the insulated crown molding doesn't work and isn't worth pursuing. The researchers expressed the opinion that the only solution that really works is a "chainsaw retrofit" job that includes new rigid foam on the exterior side of the wall sheathing and roof sheathing.

    Most homeowners can't afford that work, so they get by with halfway measures like the ones you are suggesting: air sealing work, the use of two-component spray polyurethane foam in the attic at the critical area, and conscientious use of exhaust fans and (in some case) a dehumidifier to lower indoor relative humidity.

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