Hi

I have a row home in Baltimore City, Maryland built in 1890. House was gutted and renovated in 2014. The floor joist for the first floor remained as they were in good condition. My basement is very dry with a little dampness near the front of the house where it meets the ground. I run my dehumidifier with a targeted humidity level of 45.

I started seeing these spots about a month ago and more are appearing. Any help of what is going on would be much appreciated! Pictures are attached.