To repair the ceiling inside…
- Scrub the mold with a solution of 5 parts water to 1 part bleach and let it dry completely.
- Lightly sand the area.
- Coat it with a stain-blocking primer before applying several coats of paint on top.
If you’ve been successful in boosting attic insulation levels in the trouble zone, the mold won’t return. If you can direct the airflow from a heating register into the ceiling corner, it will also boost your chances of success.