I was at an inspection a while back. The house was vacant and had some issues but the client was a do-it-yourself person and wasn’t too concerned about doing a little work. The basement was unfinished and I inspected it during the course of my work. There were cracks that had been repaired, some missing insulation at the rim joists and not much else. A week later, I received a call from my client. The bank appraiser was worried about mold in the basement. This was a surprise, since I did not see any mold at the time of the inspection. We arranged to meet back at the house and re-inspect the areas of concern. This is what the appraiser was seeing on the basement wall:

It was a large area of black on a basement wall and the quick assessment was that it must be mold. Fortunately, what I had observed during my inspection and what the assessor assumed were two different things.

If you have ever watched a house under construction, you’ll have noticed that the ground is excavated and foundation walls poured. While concrete is hard enough to hurt your head on, it is also porous. Water will eventually seep through unless it is water proofed. They call it “damp proofing” and typically use an asphalt-based coating that is sprayed or hand applied to the foundation walls to reduce water penetration.

Damp proofing on new construction foundation walls

So…what was the issue with the “black mold” all over the basement wall? Well, the previous owners had added a laundry room addition to the original house. The addition was a full-construction with an excavated basement. New foundation walls were poured, a stairway added and an opening was cut into the existing basement area to gain access from the newly created space. The wall with the “black mold” was the original foundation wall which was stained with that damp proofing I mentioned earlier.

You’ve heard that “all that glitters is not gold”? Well, you could also say, “all that is black is not mold”!