Red on the Mold Report: What Buyers and Agents Should Know Before Walking Away

A red number on a mold lab report is a prompt to look closer. It is not a finding that the house is sick.

That difference costs real money when it gets lost in the middle of a closing, says Barry Westbrook has spent more than two decades sorting out that confusion. He founded DocAir: Nashville’s Leading Air Quality & Building Science firm.

His starting point on any mold report is simple. “In any discussion of mold exposure, it is important to note that there is a wide spectrum between unsafe and pristine.”

Most reports land somewhere in between. Here is how to tell where.

Why Labs Flag Results in Red

Many lab platforms automatically highlight certain species because those species are linked to moisture. Chaetomium gets flagged often.

Westbrook points out that Chaetomium is a heavy spore that drops out of the air quickly. The software highlights it so the reader notices it. The goal is for you to notice, not to panic.

Context changes the reading. When counts are low, and most of the spores are common outdoor types like Basidiospores and Cladosporium, the indoor sample is usually just mirroring the outdoor air.

That is exactly what a normal house that exchanges air with the outside should show.

Every House Has Mold Spores

The EPA states that it is impossible to get rid of all mold and mold spores indoors. Spores float in the air and settle into house dust in every home.

So the useful question is not “is there mold?” The answer to that is always yes. The useful question is whether something is growing, where it is growing, and why.

Why Inspectors Write Alarming Reports

Westbrook has some sympathy for home inspectors who use frightening mold language. When asked why reports read that way, his answer is short: “The reason is simple: LIABILITY.”

Standard report wording often lists every health effect ever linked to mold. As he reads it, the inspector is passing the risk decision to the buyer or to a specialist with more experience assessing exposure.

That is a sensible move for the inspector. It becomes a problem when nobody takes the next step and the buyer treats the boilerplate as a diagnosis.

Two Tests That Often Mislead

Not every sampling method tells you what people in the house are actually breathing.

Crawlspace air samples. Westbrook describes a crawlspace spore trap test that read 49,000 spores per cubic meter. The sample was taken after an encapsulation and dehumidifier had already been installed.

The number looked like a failed job. It wasn’t. Tiny Aspergillus and Penicillium spores settle into crawlspace dust over time, and just crawling around to take the sample can stir up a cloud that spikes the reading.

He concludes that crawlspace spore trap results should not be treated as a definitive measure of air quality in the living space.

Tape lifts. A strip of tape pressed onto a floor joist confirms whether that surface residue contains mold. That is all it can tell you.

Westbrook has seen tape lift results stretched to describe an entire house. “This is pseudoscience and not a logical way to evaluate indoor air quality,” he says.

His comparison makes the point. You would not call a home contaminated because a swab found a little E. coli on one kitchen countertop.

A Sensible Plan for Low-Level Results

When the numbers are low, a step-by-step approach beats rushing to a remediation quote. Westbrook bases decisions on physical evidence, not on a single air sample.

Look for water staining, active moisture, or visible growth.
Clean first. Heavier spores are often settled dust stirred up during testing, and HEPA vacuuming usually takes care of them.
If there is no moisture source and no visible growth, a trace reading does not point to an emergency.

When growth is real, size matters. EPA guidance treats a moldy area under about 10 square feet as a job most homeowners can handle. Larger areas call for professional cleanup guidance.

The same guidance recommends keeping indoor humidity below 60 percent, and ideally between 30 and 50 percent.

Where the Real Problem Usually Sits

A report with flags but no active growth often points to a bigger issue than the flag itself. Westbrook asks one question of every house: where does its fresh air actually come from?

In most homes, air leaks in through cracks, ductwork, crawlspaces, and wall cavities. In Middle Tennessee, that unplanned air brings humidity and pollen in with it.

DocAir sums it up in one line: “The leak is the real problem, not the lab flag.”

That moves the conversation away from a remediation bill and toward how the house breathes. That is a problem you can measure and fix.

Next Time the Report Comes Back Red

Read the whole report, not just the highlights. Check for moisture and visible growth before you decide anything.

There is a wide spectrum between unsafe and pristine. Most houses with a red number on the page sit comfortably inside it.