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I've got spots on my ceiling in one of the bathrooms in my house. There are 3 spots in a straight line. They are perfectly round and very small. I am thinking they are the nail heads as magnets stick to them. The spots are cold and seem lightly damp. I am thinking it is condensation on the nail heads as they must act as a conduit for the cold to come in from the attic.

How can that be fixed? I cleaned my bathroom fan and I think it's about 15cfm under the HVI recommendations. It was very dirty, so I don't know if maybe it's not drawing out enough humidity from the air?

What should I do?

John Arg
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The nails penetrate the ceiling and some insulation so they get cold enough for condensation to form. This leads to both rust and mildew by the heads.

Before you clean up the rust and/or mildew, replace any insulation above the bathroom that may have been damaged and add additional insulation above the joists to prevent a recurrence.

DrMoishe Pippik
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