I'm currently redoing the (exterior facing) walls in my basement. I found the previous owners put up fiberglass batt insulation and covered that with plastic sheeting for insulation. As you can guess, there was mold and mildew growing where the paper facing of the batt met up against the plastic sheeting.
I tore that all out and checked the wall behind it. Fortunately there are no signs of water damage or leaks, and no signs of mold or mildew on the block wall. But I still want to prep/clean the walls before I redo the insulation (XPS foam boards) and put up new studs.
The walls do appear to have already been coated with two coats of paint or water sealant. Should I use a spray type mold and mildew cleaner, or should I coat the walls with a mold and mildew resistant primer? Or both?
If you don't have any mold, then don't apply a fungicide. It won't provide any lasting mold resistant qualities. Instead apply some paint or primer with mold inhibitors in it. See the link below for an example. However, if you have a moisture issue, even this is could be short lived protection.