Anyone has any idea what can cause this? The client says that these stains are only on his unit (end unit in the townhouse complex). I did his inspection two years ago and the stains appear only last winter. The building is 10 years old. No sign of moisture or any staining inside. Only outside. He says it was more pronounced in winter cold weather and obviously after the rain. Apparently moisture is accumulated there. Defective masonry? Lack of weep holes? Any other ideas?

The inside is causing this.

Can you elaborate on this Roy? What is exactly wrong in your opinion? What needs to be done?

I am not that familiar with brick and winter temperatures, but I would say this has more to do with thermal bridging and energy losses than moisture intrusion. The light areas would be frost and the darker areas would be dry. A good thermal inspection would probably clear this up IMO.

Thanks Brad. I offered the client to do thermal imaging when I did his inspection two years ago. He didn’t want to spend extra money. I now offered him again but he is still looking for a simple answer, which does not exist here. He suspects roof or gutters leak. But I don’t think so. It would be interesting to see what thermal imaging will show.