Ice on interior wall

[David Day]

I recently did an IR inspection of a 2 year old stick frame two story home with a basement. The owner showed me pictures of ice on the inside of some of the walls along the ceiling corner and there is water stains on these walls. He has a geo-thermal heating system and the humidity was at 30.2 %. The temperature was 69 degrees. The thermal patterns that I seen indicated moisture more so than missing insulation. One of the walls in question is a interior wall. He has an attached garage and off of the innermost wall is a small bathroom. The wall that is toward the center of the house in that bathroom is one that gets ice on it. It is not connected to an exterior wall. I am wondering what could cause these conditions. If the moisture is coming from leaks in the roof where would the cold be coming from on that interior wall? There is no 2nd floor above that bathroom. Any suggestions would be appreciated. Thanks

[Ken Rowe]

Since the bathroom has no exterior wall I would assume it has a ceiling mounted exhaust vent. I'd start there. Not knowing the weather conditions, snow on the roof, etc in your area I can only tell you what I'd look for in mine.

Exhaust vent insulation. If that vent isn't insulated condensation can form on the vent tube, dripping pretty much anywhere.

Ice dams due to roof mounted exhaust. Warm, moist air exits the exhaust vent on the roof melting the snow then re-freezing at the overhang creating an ice dam which ends up leaking into the home.

If the problem is at the wall separating the bathroom from the garage it very well could be a flashing leak where the roof meets the home (assuming the bathroom in question is on the first floor and the garage isn't two stories tall).

As for the other stains / ice at wall and ceiling junctions, again I can only assume they're on the top level of the home. I would predict ice dams as the problem.

[Jeff Zehnder]

If I was there doing a diagnostic inspection, I would just cut the Sheetrock and look. Sheetrock repairs are cheap.