The five principles behind IICRC mold remediation

In plain English

R520 opens with five principles that every later chapter builds on. In short: protect the people doing the work and the people living there; keep records of what was found and what was done; keep mold from spreading beyond where it already is; take the mold out physically rather than trying to kill it or paint over it; and fix the water problem so the growth does not come back. The Reference Guide is the explanatory companion to the ANSI/IICRC S520 Standard, so it is longer and gives the reasoning, not just the steps.

The guide treats these principles as a package. Containment and air pressure control serve both safety and source control. Documentation lets an independent assessor check the work later. Source removal is the core of the job: R520 says killing or encapsulating growth does not solve the problem, because dead mold can still cause reactions. And none of it lasts if the moisture source stays, since spores are always present at background levels and will grow again wherever water allows.

The 2024 edition of the S520 standard opens with the same five principles and sets firm requirements under the first one: workers "shall be protected from exposure," engineering controls, administrative controls and work practices come first, respirators and other PPE are added where those aren't enough, and a hazard assessment is required. It says occupants should be informed and protected, conditions and work should be documented throughout, and the return to Condition 1 should be documented before containment comes down, the structure is rebuilt or contents are reused. An independent IEP should assess the situation when health issues are reported, and contractors asked about health should send people to a healthcare professional.

On removal and verification, the 2024 standard is specific. Physical removal is "the primary means of remediation," and using sprays, fogs, foams or gases without physical removal is a departure from the standard of care. A job should be considered complete when the remediator's own post-remediation evaluation confirms the visible mold and the dirt, dust and debris with it are gone; an independent third-party IEP's verification "can provide further assurance" in some situations. If an IEP who isn't independent of the remediator does the assessment or verification, the standard says that should be disclosed to the client in writing. Last, the moisture problem should be found and fixed as soon as practical and salvageable materials dried to the S500. (Texas law goes further than the S520 here: on a licensed project, clearance by an independent licensed assessor is required.)

Texas note: these principles are best practice. In Texas, a project of 25 contiguous square feet or more of mold is regulated by TDLR under Occupations Code Ch. 1958 and 16 TAC Ch. 78, and the protocol written by a licensed Mold Assessment Consultant controls the work. A licensed Mold Remediation Contractor carries it out, and a licensed assessor who is independent of the remediator performs clearance. R520 points the same way on independence, but Texas makes it a legal requirement rather than a recommendation.

“Attempts to kill or encapsulate mold are not adequate to solve the problem”

Key points

• Protect workers and occupants with engineering controls plus respirators and other PPE.
• Document conditions before, during and after the work.
• Control contamination at its source so it does not spread.
• Remove mold physically; killing or sealing it is not enough.
• Correct the moisture problem, then dry materials before rebuilding.

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 Reference Guide, IICRC S520 Standard and Reference Guide for Professional Mold Remediation — Reference Guide — Intro, p. 8. Best practice
• IICRC S520 Reference Guide, IICRC S520 Standard and Reference Guide for Professional Mold Remediation — Reference Guide — Ch. 1, pp. 9–11. Best practice
• IICRC S520, ANSI/IICRC S520 Standard for Professional Mold Remediation — Secs. 1–1.5, principles of mold remediation, pp. 23–24. Best practice

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