Although the obvious source of moisture problems was the downstairs living room, which was just ever so slightly into the hillside, the upstairs closets were also a problem. Specifically, clothes that were stored in the closets along the north wall always smelled a bit... damp. The issue apparently was that the north wall's stucco had never been finished, or perhaps had not been applied properly in the first place. The north wall's surface is ~370 square feet. The instructions I received for making that stucco water tight were as follows:

1. Power wash it to get rid of grime and dirt
2. Seal the cracks with elastomeric crack sealer (comes in the same tubes typically associated with silicone)
3. Paint with elastomeric paint.

At Home Depot a five-gallon can of elastomeric paint costs $108. I was advised that I could cover about 100 square foot per gallon, but I would also need to apply two coats, meaning that 5 gallons wouldn't really be enough. Then there was the issue that I was likely just sealing in moisture (and rot) so this painting project lost momentum.