Home owner removed drywall to install outlets and found moisture in wall.
Home is approximately 20 years old, vinyl siding and tar paper exterior wrap. There are no penetrations of exterior wall or interior wall in area where moisture was discovered.
Moisture is located about a foot above floor sill plate on siding and no signs of moisture or staining above affected area.
Property is located in Orillia ON.
Any ideas on what could cause this one area of wall to be wet ?
Is there a type of inspection home owner could get that would correctly identify where moisture is coming from or caused by.
There was moisture that you could feel on aspenite sheathing. No signs of rotting. But no visible gap at sill plate and siding so not sure there would be a gap there. I will suggest that he caulk this areas prior to replacing insulation and drywall. Just would hate to see him replace it all and have problem reoccur.
I don’t know if you are still there, but if you have a chance to do more testing you could turn on all the bathroom fans, range hood and even run the clothes dryer to create some negative pressure inside the home and then go inspect that area some more. With thermal imaging or even you bare hands you may be able to find that there is a significant air leak there. Or not. Either way, you will learn something and be a little closer to your answer.
The guys before me already offered some good things to check, some of which you already have done.
Please do let us know if you figure this out, as we can all learn from your investigation.
JJ mentioned vapor barrier… My observation/speculation from 1400 km away, that looks like an interior air leak. That’s my first focus of investigation.
I see no sign the original air/vapor barrier was caulked at the sill plate. If that’s the case, warm, moist, interior air can enter at the base of the stud cavity and make its way to the back side of the sheathing. In this stud cavity, the dew point of the moist air is located on the OSB. Why only in one stud cavity??? Further exploration.
As a retired building contractor, I’ve seen this condition during remodeling. In winter, frost is present.
Was the air/vapor barrier poly? Look at adjacent walls. Is it caulked at the sill and top plate? Is it taped at the joints? Is the vapor barrier Kraft paper? Was the wall covered with drywall, boards, or sheet material?
Get a building contractor to look at this, one who is trained in energy conservation construction methods, and who has extensive experience with building tight homes.
Could also be a rain barrier/flashing issue on the exterior… or ???