It can grow anywhere there's moisture and "food" (which includes building materials), so if there's a leak behind a wall, sure it can grow there. Not sure what this has to do with the pearl sheen v. semi-gloss?

Paint companies make special paints for use in damp places. They have additives that inhibit mold/mildew. Benjamin Moore makes a bath/spa paint in flat which is beautiful. I've had it for over a year in our MB. It is formulated specifically for use in steamy places. Your best defense against mold is a super-duper exhaust fan on a timer that will keep running after you leave the room.

-Babka

If you have mold growing, then you have inadequate ventilation. Mold only grows in the presence of moisture. Having your exterior walls well insulated so hot steam doesn't condense on them, and then a good quality fan to duct the humidity to the exterior will work wonders for cleanliness and health.

Thanks everyone for your comments.

If mold grows on the wall's surface, can it penetrate
inside the wall (assuming there's no leak or other problem inside)?

Over time, yes. that is why you want to remove it when you see it. Bleach works.

-Babka

Thanks, Babka!

My concern is that the pearl sheen paint wouldn't resist moisture
as well as semi-gloss would...and mold might start
growing inside the walls without my seeing
any signs of it.

This post was edited by jacquelynn on Thu, Aug 7, 14 at 0:25