Be careful using partcail board in humid areas it likes to swell and break down the glue
Good thinking! I am actually installing a dehumidistat switch which will control the exhaust fan. In addition, I am going to do my best to keep air circulating through the room with additional vents and fans.
I'll keep an eye on it though, but the OSB is really there to provide a backing for the masonry rather than offer a great deal of support. If need by, I will bring in more equipment to keep air moving since the stairs sit just above the sump. The last thing I want is for the stairs to become spongy!!! :worried: