This was all over the rear side of home at stemwall but not at the front? There was a previous leak reported however No evidence was found on interior of this side of home.
What building features that may leak (windows/doors, flashings, etc) are above the water stains?
I’ll hazard a guess. Based on the fact that a weep screed is installed I’m assuming the exterior walls are wood frame. If that is the case the following scenario could be occurring. The weep screed and or the vapor barrier was installed with fasteners that were of a dissimilar metals which cause a galvanic reaction (rust). As the stucco warms during the day water vapor is moving thru the hot stucco towards the cooler side and is condensing on the vapor barrier and then moving down across the rusting fasteners and being discharged onto the exposed slab. Was that side of the home on the west or south side?
The brown stains usually come from the OSB when it gets wet and breaks down. In other words, the moisture barrier is wrong or missing. My guess is that there could be some big damage behind the stucco.
The last house I inspected that had the brown goo oozing at the weep screed needed a new diverter flashing and rebuild of entire front side…and it was a 2007 home.
Some of it looked like the glue from sill sealer.
Well if it is a stem wall, does it have a metal cap to it?
Sometimes on metal caps on stem walls have overlapped seams that let in water instead of raised or standing seams.
Was this surface staining that would rub off, or was it a chemical reaction in the concrete?
Drainage planes (house wrap) designed to be installed behind stucco are designed to drain off moisture before it enters the wall assembly. It could be that the house wrap is simply doing its job.
Just a question.Is there foundation cracks where the staining is located.From the pic,s I see all the venting , weep holes look clean so no blockage.Every visible stain(to me ) seams to have a foundation crack in the middle of the staining or beside.No staining on the conduit under stem-wall but also looks new.The paint is blistered as if where wet and moist for long periods( p1070220.)