How mold containment is built and run (S520)

In plain English

Remediators "shall" use engineering controls as needed to control airborne particles and cross-contamination. Containment (isolation or critical barriers) should keep a durable air seal for the whole job and be cleanable. The work area may lead out directly or through decontamination chambers: a "dirty" chamber for taking off contaminated clothing and wiping down equipment and bags, and an optional "clean" chamber for staging tools and waste bags. When lots of airborne dust or spores are likely, the S520 recommends a decontamination chamber as part of full containment.

Supply and return vents, building openings and fixtures in the work area should be sealed with critical barriers, and the building's HVAC confirmed sealed off or isolated from the moldy area, with an HVAC contractor if needed. Exposed plastic should be fire-retardant; the setup list calls for 6-mil flame-retardant polyethylene. Small areas of growth can be handled with source containment, but when hidden growth is suspected, larger containment should be used.

Each area has its own door, usually plastic flaps or a zipper door. Flaps open inward so contaminated air can't push out, and are sized to control airflow and pressure. Entry and exit should be direct to the outdoors where possible and kept to as few points as practical, ideally one, with multiple chambers stepping people and things down from dirty to clean.

Setting up, remediators should decide where containment is needed and what PPE is needed while building it; not disturb contaminated material until it is up; separate Condition 1 areas from Condition 2 or 3; decide which floors, walls and ceilings need plastic over them; watch for condensation or trapped moisture behind plastic; seal penetrations and holes; agree up front who repairs damage where tape meets finished surfaces; filter make-up air if needed; and hold the work area under negative pressure. The S520's minimum recommended pressure difference is -5 pascals (-0.02 inches of water column).

Before the work, remediators should review the project documents and any third-party protocol, write the work plan to the S520, and document limitations and complications; identify the work area and conditions around it; decide who is responsible for finding and fixing the moisture source; decide what contents can be saved and how they'll be handled, protecting what can't be moved; check the HVAC for water damage and mold; consider temporary heating or cooling; and set the schedule. Warning signs restricting access go at the entrance, and containment stays intact through the post-remediation evaluation.

While the work goes on, the S520 calls for at least 4 air changes per hour, with air drawn from the entry across the work area to the far end and exhausted outdoors if possible; regular checks and records of how the containment is performing; flaps built to close if pressure is lost; and stopping work whenever the containment is breached or pressure is lost, until it's repaired and pressure is back. Breaches are reported to a supervisor, the IEP or others as required. Containment isn't removed until demolition, cleanup and the post-remediation evaluation or independent verification are complete.

Texas note: on a regulated Texas project the containment requirements come from the licensed assessor's protocol and 16 TAC Chapter 78, including signs in English and Spanish and keeping walk-in containment up until clearance is passed.

Key points

• Durable, cleanable barriers; seal vents, openings and fixtures; isolate the HVAC.
• 6-mil flame-retardant poly; flaps open inward.
• Bigger containment when hidden growth is suspected.
• Don't disturb mold until containment is up.
• Minimum -5 Pa (-0.02 in. w.c.) negative pressure and 4 air changes per hour.
• Breach or pressure loss: stop work until it's fixed.
• Agree up front who repairs tape damage to finishes.

Official text

This topic is covered in our own words because the standard behind it is copyrighted; we cite it below rather than reproduce it.

Citations

• IICRC S520, ANSI/IICRC S520 Standard for Professional Mold Remediation — Secs. 9.2–9.2.3, engineering controls, critical barriers and source containment, containment access, construction considerations, pp. 46–47. Best practice
• IICRC S520, ANSI/IICRC S520 Standard for Professional Mold Remediation — Secs. 9.3–9.3.5, technical review, preliminary steps, containment set-up, signage, containment maintenance, pp. 47–49. Best practice

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