Re: Condensation inside wall cavity
It's difficult to tell sight unseen.
It may very well be from a water leak from the exterior. If liquid water is able to enter the wall cavity it will eventually heat up during warm summer temperatures and turn into vapour.
Otherwise if it is condensation occuring during warm summer temperatures -- it may be from running the air conditioner and having a poor seal between the floor and wall joint. This would allow cooled conditioned air to enter the wall cavity meeting warmer moist air from outside -- this has the potential for condensation to occur.
In this case it would be a matter of removing the base borads and sealing the floor/wall joint with either a caulk or foam in a can.
In some cases if mould is forming along the bottom portion of the wall --- a section of the drywall should be removed ( maybe to 4 ft. ) --- the vapour barrier cut --- insulation removed --- all this to provide a clearer view of what's happening inside the wall cavity.
Make the appropriate repair and put everything back together.
"" an ounce of perception -- a pound of obscure "