Mold & Indoor Air Quality Testing

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There is no federal standard for mold.

This is the single most important thing to understand before paying anyone for a mold test. The EPA has not set standards or threshold limit values for airborne mold or mold spores, and neither has any other federal agency. No sample result can show that a house complies with a federal mold standard, because no such standard exists.

That does not make sampling useless. It makes the claims some companies build around it useless. EPA describes sampling as helpful for locating a source, identifying some of the species present, and verifying that an area has been adequately cleaned after remediation. Those are real uses. "Your house failed the mold test" is not one of them.

When it is worth doing

Good reasons to sample

Something smells wrong

A persistent musty odour with no visible growth. Sampling alongside moisture readings can help narrow down where it is coming from before anyone opens up a wall.

Symptoms indoors

Occupants feel worse in the building than out of it, and you want documentation of conditions rather than a guess. Useful as a baseline, not as a diagnosis.

After remediation

Verifying that cleanup actually worked. Post-remediation samples should resemble local outdoor air. This is one of the clearest uses EPA identifies.

When it is not

When I will tell you to save your money

You can already see it. EPA's position is that when visible mold growth is present, sampling is generally unnecessary. The growth is the finding. Spend the money on finding the water instead.
You want a clean bill of health. A single air sample captures one moment in one location. It cannot certify a house as mold-free, and no honest report will say it does.
Nobody has looked for moisture yet. Mold is a symptom. The key to mold control is moisture control, and a lab result that arrives without a moisture source identified has not solved anything.

What I do

Moisture first, samples second.

Before any sample is taken I walk the building with a moisture meter and thermal camera, looking at the places water actually gets in — roof and flashing, grading and drainage, plumbing penetrations, crawlspace ground cover and ventilation, window and door sills, and the areas around tubs and showers. Finding a wet wall cavity is worth more than a spore count.

Where sampling is warranted, an indoor air sample is paired with a matched outdoor control, because indoor numbers are only interpretable against the air outside that day. Surface swabs or tape lifts can be added where there is visible growth to identify. Everything ships overnight to an accredited laboratory, and you get the lab's written report along with my explanation of what it does and does not establish.

EPA guidance is clear that mold sampling should be done by people with specific experience in sampling protocols and interpreting results, with analysis following methods recommended by AIHA, ACGIH, or comparable professional bodies. That is the standard I work to.

Pricing

Straightforward, with the shipping included

$250 — add-on

Added to a home inspection on the same visit. Includes the indoor sample, matched outdoor control, and overnight lab shipping.

$350 — standalone

A separate visit, for homeowners not buying or selling. Same sampling and lab work, priced to cover the trip.

Moisture assessment

Included in every home inspection at no extra cost. Thermal imaging and moisture readings across the areas where water usually gets in.

Discounts apply to the base inspection fee only, never to add-on services.

Questions

Common questions

Is there a legal limit for mold in a house?

No. Neither EPA nor any other federal agency has set standards or threshold limit values for airborne mold or mold spores. That means no sample can tell you a house passes or fails, because there is nothing to pass or fail against. Anyone who tells you a house is over the legal limit is selling something.

Then what is sampling actually good for?

Three things, per EPA guidance: helping locate a source when growth is suspected but not visible, identifying some of the species present, and confirming whether an area has been properly cleaned after remediation. After remediation, indoor samples should look broadly similar to outdoor air.

If I can already see mold, should I test?

Usually not. EPA is direct about this: in most cases, if visible mold growth is present, sampling is unnecessary. Visible growth is the finding. The money is better spent identifying the moisture source and correcting it, because mold that is cleaned without fixing the water comes back.

What does the test involve?

An indoor air sample plus a matched outdoor control sample, since indoor results only mean something compared against the air outside that day. Where there is visible growth, a surface swab or tape lift can be taken as well. Samples ship overnight to an accredited laboratory and results come back as a written report.

How fast do I get results?

Samples ship overnight and lab turnaround is generally a few business days. Overnight shipping is included in the price.

What does it cost?

$250 as an add-on to a home inspection, or $350 as a standalone visit. Overnight lab shipping is included either way.

Can you remediate what you find?

No, and that is intentional. I test and report; I do not sell remediation. An inspector who profits from the cleanup has an obvious reason to find a problem. If a sample warrants remediation I will tell you what the lab found and you can hire independently.

Sources. U.S. EPA, Mold Testing or Sampling and Mold Course Chapter 3; EPA, A Brief Guide to Mold, Moisture and Your Home (402-K-02-003); analytical methods per the American Industrial Hygiene Association and the American Conference of Governmental Industrial Hygienists.