Mold 6. Cleanup

Cleaning Up Mold & Rot: Building Remediation


  • Remove conducive conditions immediately, such as:
  • Stop the moisture sources immediately.
  • Improve drainage and ventilation immediately.
  • Dry or remove damp materials immediately.
  • Remove mold damaged surfaces and rotten areas.
  • Vacuum clean/brush dry moldy surfaces.
  • Clean, rebuild, and paint.


  • Wear an air purifying respirator with a HEPA filter cartridge.
  • Wash work clothing often, separately.


Isolate and ventilate the work area to avoid spreading moldy dust into clean areas:

  • Use an exhaust fan in a window near the work area to suck out dirty air and blow it outdoors (to keep the work area under negative pressure vs. clean areas).
  • Use a filter on the fan to avoid impacting others outside. And sometimes:
  • Build containment walls with plastic sheets around the work area to direct the ventilation flow most effectively.
  • Use a fan like a 20-inch box fan in a window with the opening around the fan blocked with a sheet of plastic or plywood.
  • Use a fan in a window away from the the work area, to blow outdoor air into the living areas to pressurize, ventilate, and help exhaust out through a window near the work area (or out through the attic or crawl space access hatch, work area, and vents).


  • Establish good ventilation, as described above.
  • Cover small or interesting moldy surfaces with clear self-stick carpet masking tape (2 feet wide) to contain the mold yet keep the evidence visible, and for easy intact removal.
  • Remove a moldy carpet by covering it with plastic sheet, rolling it tightly, and wrapping in plastic.
  • Dry the space with dehumidifiers, or by ventilating with fans and outdoor air or warm house air, or by having a professional drying service pump warm, dry air through it.
  • Dry inside wall cavities by pumping warm, dry air through openings near the floor.
  • Open walls as far as necessary to find and remove any moldy materials.
  • Open and inspect any wall that has water stains or a moldy odor.
  • Remove all structurally damaged materials, and moldy porous, soft materials.
  • Remove any rotten materials.
  • Wrap moldy materials in plastic for disposal.
  • Inspect for signs of wood destroying organisms (WDOs) such as wood rot fungus or insects (beetles, termites, ants).
  • Remove and replace moldy sheetrock, or:
  • Vacuum clean dry mold, using a brush attachment & HEPA filter. And/or:
  • Wet wipe and wash moldy surfaces with detergent, rinse with water, and dry.
  • Sanitize if you feel it necessary, using fungicide solutions such as bleach (peroxide bleach safest; avoid hazardous chlorine bleach), borate, quats (quaternary ammonium salts); paint with added zinc.
  • Paint over the stained remediated area (using breathable stain-blocking latex primer & paint) to lock down the few remaining particles, and cover obvious stains from past mold, and see if new mold ever grows again.
  • Seal the surface with pigmented shellac if a vapor barrier is needed.  Or:
  • Seal with a silicone-quat for extra continuing antimicrobial protection.
  • Rebuild with new materials.
  • Watch to see if mold ever grows again.
  • Clean mold growth from the bathroom and windows often.


  • Unblock eave vents by moving insulation away, and keeping baffles open.  Don’t paint over fine screens.
  • Cut a large opening in a gable end to use for a work access door (perhaps with a louvered vent).
  • Build a central attic walkway 2 feet wide.
  • Remediate mold growth (as described above).
  • Install a continuous roof ridge vent, and large gable end vents.


  • Remove all debris (wood, cardboard forms, rodent droppings), the old plastic ground cover, and moldy surface soil.
  • Remediate mold growth (as described above).
  • Re-cover exposed soil with black plastic sheets to reduce the release of moisture.
  • Seal penetrations through duct joints and floor, such as for air ducts, electrical wiring, outlets, plumbing (with metal foil or duct tape, caulk, polyurethane foam, weatherstripping, and gaskets) to avoid air rising into the living area.
  • Add more perimeter vent holes; have them on at least three sides.
  • Keep perimeter vent holes open and screens clear.


  • Clean carpets, fabrics, furniture, furnishings, and other interior surfaces well.
  • Use a vacuum cleaner with high efficiency filters. Or better yet:
  • Dry steam clean (not wet shampoo) the carpets and furniture.
  • Wet wipe horizontal surfaces.
  • Clean the insides of the hot air ducts.


  • Fumigate the unoccupied house with much ozone for a day or more to reduce mold odors remaining in inaccessible locations, such as within the wallboard; then ventilate well with windows and exhaust fans a few hours or more.

DISCLAIMER: These general recommendations may not solve all your problems.

THE END of “Mold and Moisture Problems in Buildings”

©2004-2019 Richard Knights, Blue Sky Testing LLC
Salem, OR & Seattle, WA,