Fiberglass insulation in below grade wall


Old 11-06-02, 09:56 AM
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Fiberglass insulation in below grade wall

I'm remodeling my house which had no insulation in the exterior walls. I put some fiberglass insulation in a below grade wall before I knew any better. The wall was previously exposed concrete that seemed very dry. Are there potential problems with this?


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Old 11-16-02, 04:32 AM
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Concrete is porous and water can difuse through it. It appears dry due to evaporation of the small amount of moisture making its way through the wall. If you use a rigid insulation such as polystyrene it can go dirictly on the concrete wall. Polystyrenes R value is unaffected by moisture and an additional vapour barrier on the warm side of the insulation is not needed. Besure to caulk all seams. If it is fiberglass batt, a moisture barrier of poly or felt paper should be placed against the wall before you fur and insulate. This barrier protects the wood & insulation from the dampness.If the insulated wall is below grade leave batt insulation up off the floor about six inches. If minor flooding in the basement occurs the insulation stays dry. Once batt insuation is in place use a poly vapour barrier, overlapping and sealing all joints. The vapour barrier prevents warm moist interior air from entering the insulation and condensing against the cooler concrete . Damp batt insulation looses its effectivness
Old 11-16-02, 07:22 AM
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See for RB paint additives for concrete paint for basements.

I furred my walls out with 1x2 and attached a single layer RB then the dry wall. This performs better than fg or foam, is non carcenogenic , does not condensate moisture and mold will not grow on it.
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