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Mold Remediation Standards and Certifications

Understand the industry standards and certifications that define quality mold remediation, so you can evaluate contractors and ensure your project is done right.

Why Industry Standards Matter

Mold remediation is an unregulated industry in most states. Without licensing requirements, anyone can call themselves a "mold remediation specialist." Industry standards provide the benchmark for professional, safe, and effective work.

When you hire a contractor who follows established standards, you get:

  • Procedures developed by scientific and industry consensus
  • Consistent methodology that has been proven effective
  • Protection from shortcuts that could harm your health or property
  • Documentation that supports insurance claims and legal matters
  • Objective criteria to evaluate whether work was done properly

The IICRC S520 Standard

The ANSI/IICRC S520 Standard for Professional Mold Remediation is the authoritative guideline for mold remediation in the United States. Published by the Institute of Inspection, Cleaning and Restoration Certification (IICRC), it represents the consensus of microbiologists, industrial hygienists, remediation professionals, and public health experts.

What S520 Covers

  • Assessment and documentation procedures
  • Containment and worker safety requirements
  • Cleaning and removal methods by material type
  • Post-remediation verification standards
  • Communication and documentation protocols

Key Principles

  • Source removal is primary—not chemical treatment
  • Containment prevents cross-contamination
  • Different materials require different approaches
  • Independent verification confirms success
  • Documentation protects all parties

The Core Principle: Source Removal

The most important concept in S520 is that physical removal of mold contamination is the primary means of remediation—not killing mold with chemicals.

Section 4.4 of the standard states: "Physically removing mold contamination is the primary means of remediation. Attempts to kill or encapsulate mold generally are not adequate to solve the contamination problem."

Understanding Conditions 1, 2, and 3

The S520 standard uses a "Condition" system to classify environments. Understanding these terms helps you interpret inspection reports and remediation plans:

Condition 1

Normal Fungal Ecology

An indoor environment where mold spores are present at levels similar to outdoor air—this is normal and unavoidable. Condition 1 is the goal of every remediation project.

Condition 2

Settled Spores

An area contaminated with spores that spread from elsewhere (a Condition 3 area), but without active mold growth. Requires cleaning but not material removal.

Condition 3

Actual Growth

An area with actual mold growth—visible or hidden, active or dormant. This is where remediation focuses and often requires material removal.

A proper remediation project will identify all Condition 3 areas, address the moisture source, remove contamination, clean Condition 2 areas, and verify that all spaces return to Condition 1 before declaring the project complete.

Professional Certifications to Look For

While no certification guarantees quality work, these credentials indicate formal training in industry standards:

Remediation Certifications

  • IICRC AMRT (Applied Microbial Remediation Technician)
  • IICRC CMR (Certified Mold Remediator)
  • ACAC CMRS (Certified Mold Remediation Supervisor)
  • RIA MRS (Mold Remediation Specialist)

These certifications indicate training in proper remediation techniques.

Inspection/Assessment Certifications

  • ACAC CMI (Certified Mold Inspector)
  • ACAC CIE (Council-Certified Indoor Environmentalist)
  • IICRC CMI (Certified Microbial Investigator)
  • ASHI Certified Home Inspectors (for general assessments)

Inspectors and assessors should be independent from remediation contractors.

What to Expect from Certified Professionals

When you hire a contractor who follows S520 standards, your project should include these elements:

  1. 1

    Thorough assessment

    Before work begins, you should receive a written scope of work identifying all affected areas, moisture sources, and proposed remediation methods. An independent assessment by a qualified Indoor Environmental Professional (IEP) is recommended for significant projects.

  2. 2

    Proper containment setup

    Work areas are isolated with plastic sheeting, and negative air pressure (-5 Pascals minimum) is maintained to prevent spores from spreading. You should see air scrubbers running continuously and workers using appropriate protective equipment.

  3. 3

    Source removal, not just treatment

    Contaminated porous materials (drywall, insulation, carpet) are physically removed and disposed of. Semi-porous materials (wood) are cleaned using HEPA vacuuming and appropriate cleaning methods. Non-porous materials are wiped clean.

  4. 4

    Moisture source addressed

    The water source that caused the mold is identified and corrected. Remediation without fixing the moisture problem is pointless—mold will return.

  5. 5

    Documentation throughout

    Reputable contractors document pre-remediation conditions, work in progress, and final results with photos. You should receive copies of all documentation.

  6. 6

    Post-remediation verification

    After work is complete, an independent inspector verifies the area has returned to Condition 1. This verification should not be performed by the remediation company.

For more details, see our guides on containment and negative air and post-remediation verification.

Red Flags: When Standards Aren't Followed

Be cautious if a contractor:

  • Primarily relies on chemical sprays, foggers, or "mold bombs"
  • Cannot explain how they will contain the work area
  • Offers to do both inspection and remediation without independent verification
  • Provides no written scope of work or contract
  • Guarantees "mold-free" results (impossible—mold spores are everywhere)
  • Uses scare tactics about "toxic black mold" to pressure immediate decisions
  • Cannot provide proof of training, certification, or insurance
  • Offers prices dramatically lower than other quotes
  • Refuses to address the moisture source as part of the project
  • Does not recommend post-remediation verification

For more warning signs, see our guide on mold scams and red flags.

Questions to Ask Contractors

Use these questions to evaluate potential remediation contractors:

Get free access to the full guide

16 questions across standards, process, and verification

Use our contractor vetting guide for a complete checklist, and our cost estimator to prepare realistic budget expectations.

Official Resources