I looked at an 8 year old townhome today and from street view, it looked pretty good. How quickly things can unravel.
In the basement in pic #1, there was a lot of moisture staining and rot in the rim joist and subfloor area. At first I thought it was primarily a grading issue as the front grades were too high against the stone siding. But after seeing how high the moisture damage appears on the basement ceiling, I knew it had to be more than grading and suspected the chimney. You'll also notice in pic #1 the award winning flue install and I-joist modification. How many crap defects you jam into a 1 foot sqare area?
Pic #2 shows a front view of the house where I saw ants early in the inspection at grade level and on the wall but I didn't think much of it at the time. I took this pic at the end of the inspection after visiting the attic. You'll see why soon.
Pic #3 shows the flue pipe chase and staining on the wall in the attic.
Pic #4 shows a closeup on the inside of the chimney chase next to the flue pipe and a lot of water damage and deterioration.
Pic #5 shows what happened after I moved some insulation away from the wall and floor. The ants just kept pouring out.
Pic #6 is a view of the front of the house showing where the ants appeared to enter and where they showed in the attic
The main source of the leak into the chase appeared to be at the junction if the chimney chase with the roof. Based upon the amount of damage I saw, it looks as though this has been going on for quite some time. I have my doubts there is any flashing installed at the water entry point.