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Cause of water within an unconditioned space?

bruceshda | Posted in General Questions on

I have a situation in an existing building where water is building up on the underside of an exterior steel pan/concrete tread stair. The space below is an enclosed, unconditioned storage room. I’m assuming the water is from condensation due to the temperature differential between the exterior and interior surfaces.

I’m thinking of insulating the underside of the stair but want to confirm this is the best solution. Or, are there other ideas, such as vapor retardant paint which could work as well.

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  1. GBA Editor
    Martin Holladay | | #1

    It's hard for me to visualize. Does this room have a ceiling? Or is the room exposed to the sky?

    Is the steel stairway the only ceiling on this room?

    If the steel stairway is the room's ceiling, and there is no insulation under the stair treads and risers, then your suggested solution will work. You need to install some foam insulation to separate the cold risers and treads from the room below.

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