Hi. I would really appreciate some advice on a major issue that has arisen on a newly installed roof. I’m a new first-time homeowner. In August, I hired a roofing company to replace the old roof on my recently purchased home. They removed three layers of shingles, put plywood over the existing tongue and groove sheathing, and put the new shingles and flashing on. Now, about 2 months after installation, some black mold has appeared on the undersides of the tongue and groove sheathing in the attic. (I’m getting a professional mold / mildew assessment performed this coming week).
I’m baffled by the sudden appearance of black mold because the roofers installed ridge venting and smart vents, which would hopefully be as good or much better than previous ventilation. There had been evidence of previous water damage in the roof, but no black mold. The mold that has appeared is in the area where a chimney had previously abutted the home. We got the chimney demolished shortly before the new roofing. I looked at a photo I took of the home when all the old shingles had been removed and when I blew it up, I noticed that the wood around this area seems kind of dark. The black mold in the attic is occurring right below this spot. I’m guessing that there was some wood rot in the tongue and groove sheathing around the chimney area (perhaps from inadequate prior flashing around the chimney) and the roofers did not remove it. Perhaps the new roof work stirred up mold spores in the possibly rotted tongue and groove?
I’m really concerned about this, especially since if the original tongue and groove sheathing was rotten in this area, it has now been covered by a new plywood layer the roofers installed. It seems it will be difficult to assess the condition of the tongue and groove sheathing now that it’s been covered and it will be difficult to remedy. Any thoughts on why the mold has appeared and how to address the possible rot in the old sheathing that’s been covered?