










Mysterious odour and stainings
Canada, Ontario.
I moved into a townhouse (built in 2022) in February 2026.
There has been a persistent unusual mould-like odour in the ensuite shower room since basically the beginning. More recently, another person who inspected the unit described the smell as somewhat sweet.
On March 3, an independent IAQ company inspected the unit. Their lab results later identified a very low level of Chaetomium in the ensuite. At that time, their moisture meter did not identify actively wet areas and they did not find a significant visible mould source.
The smell never really went away.
On August 4, I found new yellow and brown spotting and streaks appeared at the upper ceiling corner of the ensuite. If the unit's layout upstairs the same, this area is under a dishwasher upstairs. There's quite plumbing there: kitchen and a pipe from the combi-heater/AC.
I'm trying to inspect the cavity in a non-destructive way with my borescope camera. I can't reach the places in question and limited to exploring the framing around.
I don't understand what I see and asking for help.
Does it require cutting the drywall?