If you’ve scrubbed a spot and it keeps coming back, the problem is behind the drywall, not on it. Other signs: stains that bleed through new paint, paint that bubbles or peels, drywall that feels soft or warped, and a musty smell you can’t pin down to anything in the room. Walls backing onto bathrooms, kitchens, and laundry rooms are the usual trouble spots in Birmingham. A slow plumbing leak can drip inside a wall for months before anything shows on the surface. Older homes in neighborhoods like Highland Park, Forest Park, and Crestwood are another common source, where settled insulation and missing vapor barriers let warm, humid Alabama air condense inside cooler wall cavities. Don’t wait on it. Mold spreads quietly behind a wall, and the longer it sits, the more framing and insulation you end up replacing once somebody finally opens things up to take a look.