Why the bathroom wall has ice on it?

10/7/2020 at 8:50:03 AM

Hi Terrii,

It would be very difficult to diagnose this problem without additional information.

The soft spots you are finding are likely air pockets behind the paint and probably water damaged plaster or drywall.

It could be from inadequate ventilation of your bathroom (evacuating warm moist air from the interior).

It is possible that your home is not insulated (perhaps double brick) or poorly insulated (in the case of stick framing).

If the temperatures where you are (I believe you are in the mountains) gets cold at night, the colder temperature can be reaching the back of the interior wall sheathing (drywall or plaster).

When warm moist air contacts the cold surface, the water vapour immediately condenses on that surface changing back from a gas (steam) to liquid (water) and if the temperature at that spot is below 0 degrees Celcius, to a solid (ice).

The wall should really be opened around this spot.

Address any deficiencies in the insulation, check outside for deficiencies in the exterior veneer (brick, siding, stucco, etc.), check attic for any leaks in the roofing in this (or any) area, remove any water damaged plaster or drywall, ensure water condensing in the wall cavity is or has not damaged areas below the ice (rim joist area between floors),a and then repair, patch, and paint.

Good luck