Why containment matters
Disturbing mold, by cutting out drywall, pulling up carpet or scrubbing surfaces, releases spores and fragments into the air. Without containment, those particles can spread through the house and settle in clean areas, ductwork and belongings. Containment isolates the work area so cleanup doesn't create a new problem elsewhere.
How containment is set up
The level of containment depends on the size and location of the affected area. Common measures include:
- Plastic sheeting barriers that seal off the work area from the rest of the house, often with a zippered door for entry.
- Negative air pressure, created by an air scrubber or fan that pulls air out of the contained area through HEPA filters and exhausts it, usually outdoors. This keeps air flowing into the work area rather than out of it.
- Sealing HVAC vents in the work area and shutting down the heating and cooling system if it serves the area, so spores aren't drawn into ducts.
- Covering floors and items that stay in or near the work area.
- Decontamination areas for larger jobs, where workers remove protective clothing before leaving the containment.
- Bagging and sealing debris inside the containment before it's carried out.
Small areas
For very small areas of surface mold on non-porous materials, extensive containment may not be necessary. Public health guidance generally says homeowners can often clean small areas themselves, with protective gear and good ventilation, as long as the moisture problem is fixed. Larger areas, mold in walls or HVAC systems, contamination from sewage, and situations involving people with health concerns are better handled by professionals.
Protecting the people in the house
During remediation, keep children, pets and anyone with respiratory conditions away from the work area. Ask the contractor how long the work will take, whether any rooms will be unusable, and what precautions they recommend. Workers inside containment should wear appropriate protective equipment, including respirators.
HVAC systems
If mold is found in ducts, the air handler or around the evaporator coil, the HVAC system should be addressed as part of remediation. Running a contaminated system can spread spores. Coordinate with an HVAC contractor where needed, and replace filters after the work.
Questions to ask
- What containment will you set up, and why that level?
- Will you use negative air pressure with HEPA filtration?
- How will you protect my HVAC system?
- How will debris be removed from the house?
- Which rooms will be off-limits, and for how long?
Air scrubbers and HEPA filtration
Air scrubbers draw air through HEPA filters, which are designed to capture very small particles, including mold spores. In remediation, they serve two purposes: creating negative pressure in the contained area, and cleaning the air in and around the work area. Ask how many air scrubbers will be used, where they'll exhaust, and how long they'll run after removal is complete.
After containment comes down
Containment should stay in place until removal and cleaning are finished and the area has been checked. Removing plastic too early can release settled dust. Once it comes down, the area should be HEPA vacuumed and wiped again, and HVAC filters replaced. If you're using independent clearance testing, it's usually done before the containment is removed.
Cost and scope
Containment adds labor and equipment to a job, and its scope should match the size of the problem. Ask the contractor to explain why they chose the level they did, and what changes if more mold is found once walls are opened.