· by Michael Blair, Nashville's Drywall Repair
Drywall that has been wet loses strength, and gypsum plus paper plus Middle Tennessee humidity is a reliable substrate for mold. Painting over the evidence does neither the leak nor the board any good.
Fix the leak first
Obvious and routinely skipped. A ceiling stain repaired without finding the source reappears, and by then the surrounding board has been wet for longer.
Water travels along joists before dripping, so the stain is rarely directly below the entry point.
What has to come out
Any board that is soft, crumbling or visibly moldy. Drywall wicks water upward, so cut back further than the visible stain — commonly to the next stud beyond it.
Wet insulation in the cavity must come out too, whatever the surface looks like.
- Find and fix the source before repairing
- Cut back past the visible damage to sound board
- Remove wet insulation from the cavity
- Dry the cavity fully before closing it
- Stain-blocking primer, not ordinary primer
Dry before closing
Framing and cavity have to be dry before new board goes on. In Middle Tennessee humidity that takes longer than it looks, and a moisture meter is more reliable than judgment.
Closing a damp cavity produces exactly the mold problem the repair was supposed to prevent.
Stain blocking
Water stains bleed through ordinary primer and latex paint, often reappearing weeks later. A shellac or oil-based stain-blocking primer is what seals them.
This applies even where the board is sound and only the surface is marked.