Would say this was construction mold? Home is 15 years old. Several areas on b floor joist. Home has been vacant for sometime. Should I recommend a mold test?
Thanks!
Yes, most likely that lumber was installed originally with some mold on it and this mold just grew larger as the environment allowed. Plywood because of the air gaps between plys (retains moisture better) and the glue used (supposed better desired food for mold) will grow mold faster and at a lower humidity and wood moisture level then framing lumber.
Yes, I would recommend testing by somebody who is certified to do so.
James,
Thanks! I did.