Greetings from Bellingham, Washington. Long time handyman, first time poster here.
A friend is convinced she has mold growing in her living room and is concerned her whole trailer is going to collapse from rot due to it. I'm not so sure it is mold.
This is a 1960's vintage mobile home with 2x framing and insulation with vinyl siding. Electric heat and cooking. The suspected mold is concentrated on the inside of the walls, over the studs, very pronounced on the sheetrock nail heads and only on the north side of the building. You can see the black concentrations directly along the framing studs in the picture.
She tells me she keeps the house pretty much zipped up tight in the winter, however, there is a decent amount of infiltration through the windows and such. There is only a hint of blackening in the kitchen (no picture.)
The discoloration first started appearing about 8 years ago and was very faint. Each winter it darkens and becomes more pronounced. This year, we had a significantly more severe winter and coincidentally, she noticed soot from her oil candles forming on the ceiling. You can see two blotches on the ceiling above the oil lamps.
She says the lamps are burning almost all winter. (She likes the ambiance.)
Anyway.... I tell her there's a pretty good chance those black accumulations are not mildew and are probably soot condensing on the cold studs.
She doesn't seem convinced and fears the worst.
How can I prove it to her either way (mold vs soot?)