Post-Remediation Verification (PRV)

Post-remediation verification is the term IICRC S520 uses for the independent evaluation performed after remediation and before containment is dismantled. Clearance testing is the same thing in plainer language. If you work in restoration you probably say PRV, and if you are a homeowner you probably said clearance, and both of you are looking for the same document.

This page is the technical version. It covers what S520 actually asks for, what the verification consists of, what the criteria are, how we handle a failure, and what it costs. We are an independent testing firm. We perform no remediation of any kind and take no referral compensation, which is what makes a PRV from us usable as evidence rather than as paperwork.

What S520 says and does not say

The ANSI/IICRC S520 Standard for Professional Mold Remediation is the recognized industry standard for this work in the United States. It defines Conditions 1, 2 and 3 for indoor environments: Condition 1 is normal fungal ecology, Condition 2 is settled spores or fragments dispersed from a Condition 3 area, and Condition 3 is actual active growth. The objective of remediation under S520 is to return the affected area to Condition 1.

The standard is explicit that verification should be performed by an independent party, and it is equally explicit that it does not prescribe a single numeric pass threshold. There is no federal or ANSI number that says "under X spores per cubic meter equals clean." Anyone who tells you there is a universal numeric standard is selling something. What S520 provides is a framework: the area should be visibly clean, dry, free of remaining contaminated materials, and its airborne fungal profile should be consistent with an unaffected reference environment.

That is why the outdoor control sample is not optional. It is the reference environment. Without it there is no basis for the comparison the standard is asking you to make.

Neither Washington nor Idaho licenses mold assessment or remediation, so S520 is not enforced by any state agency here. It is enforced by contracts, by carriers, and by what happens in litigation. New York is the outlier that made independence statutory: Labor Law Article 32 bars a single company from performing both the assessment and the remediation on the same project. In Washington and Idaho you are free to certify your own work. You are also free to discover, two years later, that certifying your own work was the weakest link in your file.

PRV protocol

A standard residential PRV is 45 to 60 minutes on site. The protocol below is what we execute unless the project's written remediation protocol calls for something different, in which case we test against that document.

1. Documentation review

Before we sample, we want the remediation scope or protocol, the moisture documentation, and the drying log if structural drying was part of the job. A PRV is a verification against a scope. Without knowing what the scope said, we can only report general conditions, which is a weaker document.

2. Containment and engineering controls

We verify the containment is still up and functioning: poly integrity, sealed seams, sealed penetrations, negative pressure differential confirmed, air filtration devices running, decontamination chamber present where the scope required one. If containment was taken down before the PRV, the verification is compromised. The sample would characterize the building rather than the work area, and cross-contamination from the demolition phase can no longer be ruled out. Do not break containment before clearance.

3. Visual inspection

The visual is the first pass and the most common failure point. We are looking for:

• Remaining visible fungal growth on any surface in the work area
• Remaining porous or semi-porous materials that were within the scope of removal
• Cleaning quality on framing, sheathing, subfloor and structural surfaces
• Settled dust and debris, including on horizontal surfaces above eye level
• Staining that requires surface sampling to characterize

A visual failure ends the PRV before air sampling. There is no point paying lab fees on an area that has visible growth in it.

4. Moisture and psychrometrics

Pin and pinless moisture meters on framing, sheathing and subfloor, referenced against a dry standard from unaffected material of the same type in the same structure. Thermal imaging where a temperature differential suggests retained moisture behind a surface. Psychrometric readings inside and outside containment: temperature, relative humidity, dew point.

Material that is still wet will regrow. Air data from a wet assembly is a snapshot of a process that has not finished, which is why moisture verification precedes the air result in our reporting order.

5. Air sampling

Spore trap cassettes, Air-O-Cell or Allergenco-D, drawn by a calibrated pump at a measured flow rate over a measured interval so that the lab reports a defensible spores per cubic meter figure. Standard sample set:

• One sample inside the containment, collected with aggressive agitation of surfaces where the protocol calls for it
• One outdoor control, upwind of the structure, collected the same day under the same weather
• Additional samples in adjacent unremediated space where the scope, the carrier or the property manager requires them

Samples go to an accredited laboratory for direct microscopic examination, which reports both total counts and genus level identification.

6. Interpretation

The lab gives numbers. Interpretation gives you a result. We evaluate:

Total count relative to the outdoor control. Indoor should be at or below the outdoor total for the same day. Substantially higher indoor counts inside a supposedly cleaned containment are a fail.

Genus profile relative to the outdoor control. This carries more weight than the raw total. The outdoor air in the Inland Northwest is usually dominated by Cladosporium, Basidiospores, Ascospores and seasonally Alternaria and Epicoccum. Those genera indoors at or below outdoor levels are unremarkable. Water damage indicator genera are the ones that matter: Stachybotrys, Chaetomium, Ulocladium, and Aspergillus/Penicillium at levels well above the outdoor baseline. Those do not arrive by infiltration in meaningful numbers. Their presence inside a cleaned containment, absent outside, indicates remaining growth or incomplete cleaning.

Hyphal fragments. Elevated fragment counts point to disturbed growth that was not fully removed or captured.

Moisture content. Above dry standard in in-scope materials is a fail on its own terms even with clean air.

7. Report

Written report with photographs, containment observations, moisture and psychrometric data tables, the raw lab report attached, the indoor to outdoor comparison shown side by side, and a stated pass or fail with the reasoning. Lab turnaround is normally 1 to 3 business days and the report follows within a day of that. Rush 24 hour lab is available for an additional $100.

When a PRV fails

A fail is a defined outcome with a defined remedy, not an accusation. The report states which criterion failed and where. Typical fails and what they usually take to correct:

Re-test is billed at the same $375 rate. There is no premium for a failed job and no financial upside for us in failing one. We have no remediation arm to feed.

Pricing

• Post-remediation verification, restoration partner rate: $375 flat, up to three samples including the outdoor control
• Additional samples: $100 each
• Rush 24 hour lab: add $100
• Re-test after correction: same $375 flat rate

For comparison, a standard homeowner mold inspection, which is a different service with a different scope, is $425 including one indoor air sample plus an outdoor control, with additional samples at $100 and a typical three sample job landing near $525.

Frequently asked questions

Is PRV the same as clearance testing? Yes. PRV is the S520 term and the one contractors and carriers tend to use. Clearance is the common name. Same site visit, same samples, same report.

Do you write remediation protocols too? Yes, and we do not bid the work that follows from them, because we do not do remediation. If we wrote the protocol we can also perform the verification against it, and that sequence is fine precisely because we are not the party doing the cleanup in between.

Can the remediation contractor be present during the PRV? Yes, and we prefer it. Being present means you see the visual findings in real time and can often correct a minor issue on the spot before we pull air. It costs you nothing and it saves a re-mobilization.

What if my carrier or the property manager specifies their own criteria? We test against whatever written criteria the project is governed by. Some carriers and some commercial property managers have their own thresholds. Send them over before the visit and we will report against them explicitly.

Do I need a PRV on a small job? Not always. On a contained job with structural demolition, an insurance file, a tenant complaint, or a pending sale, the answer is almost always yes. On a twelve square foot bathroom ceiling with no claim behind it, the cost may not be justified and we will tell you so.

How many samples do I actually need? Most single-containment residential jobs need two, one inside and the outdoor control. Multiple separate containments need one per containment plus the single outdoor control. The $375 rate covers up to three.

Schedule a PRV

We schedule around live containments and prioritize restoration partners because we know what an idle containment costs per day in equipment and labor. Call to set a standing arrangement or book a single verification anywhere in Spokane County or Kootenai County.