Procedures for effective mold inspection & testing in buildings:

How should home inspectors handle inspections for mold contamination in buildings? How would a home inspector recognize a mold problem? Are there health risks and other special environmental risks and concerns for home inspectors entering moldy areas? This document answers these and similar questions. This presentation and paper provide advice to building inspectors intending to inspect or test for toxic or problematic mold indoors, addressing inspection methods, how to find mold, where to look, what is likely to be important or not, and what inspection methods and mold test methods are valid or invalid.

Basic Facts About Basement Water Entry and Mold

This article is based on classes taught by Daniel Friedman for building inspectors.

Article Contents

• MOLD INVESTIGATION PROCEDURE TIPS
  • IS MOLD TESTING NECESSARY ?
  • MOLD INSPECTION HEALTH RISKS
  • BUILDING OWNERS INSPECTION TIPS
  • VALID INSPECTION & TEST PROCEDURES
  • HOW MUCH MOLD IS A PROBLEM?
  • WHAT TO DO ABOUT MOLD CONTAMINATION

From our environmental investigation and lab work on "sick buildings" I've learned some things about inspecting and testing for mold that have helped our general building inspection skills and which suggest some warnings to home inspectors. The first warning is that you need to determine if you should be performing a mold inspection or test by considering your expertise and by a review of the needs of the client.

Should We Test for Mold at All?

Watch out: a superficial "mold test" or "mold inspection" may be inexpensive but also dangerous as there is a high risk of failing to observe or detect unsafe building conditions that may put occupants at risk of serious, even fatal illness. At the same time a building professional should not perform expensive services where they are not appropriate.

See MOLD / ENVIRONMENTAL EXPERT, HIRE ? for help in deciding if and when a professional inspection for building mold contamination is appropriate.

Do we need to test for mold at all? Mold screening tests, as part of a thorough inspection, can help us decide when invasive inspection is needed in a building where there is no large visible mold reservoir.

Do we need to test mold in buildings to identify it? After all if all mold that grows indoors is harmful, why test it at all? Identifying cosmetic mold - that does not need to be tested - can be done by eye if you know what to look for.

See COSMETIC MOLD, RECOGNIZE

But if a building occupant has building related health complaints his or her doctor may want to know what molds are present, and there are other reasons to know what molds were present before beginning a mold clean-up job.

See MOLD TEST REASONS

Most inspectors get pretty good at spotting the history of water entry in a building. But I've inspected houses that had severe mold with no evidence of leaks. In one house, nothing suggested that there had been 20" of water on the floor. History provided by the owner told a different story. A burst-pipe put 20"of water in the basement nearly 20 years ago. They found the leak, fixed it, and had the basement pumped and "dried" in hours. Armed by hindsight one could spot very faint flood lines on paneling.

See WATER ENTRY in BUILDINGS

Flooding wasn't recurrent and there was no visible damage. Or was there? The owner pulled the paneling away from the drywall. Stachybotrys mold was so thick that it fell out in clumps onto the floor. People in the house had been sick for more than a decade, quite possibly due at least in part to this mold. You can see a photo of the owner pulling off paneling at https://InspectAPedia.com/sickhouse/0740s.jpg and our lab photo of this mold at https://InspectAPedia.com/sickhouse/1344s.jpg The mold fell right in our face! Was I wearing a respirator? Nope. I was sick with a lung infection for two weeks. Had I been a baby or elderly it could have been a more serious illness.

A Building Inspector's Guide Mold Health Risks

• Don't disturb mold. Bystanders and occupants have sued careless inspectors who cutopenings or otherwise produced a burst of mold activity in a building. Risks include contributing to illness of building occupants and contamination of building areas if substantial amounts of toxic mold are present and proper containment methods are not used.
  
  This does not mean that invasive inspection techniques are prohibited--but methods of inspection need to be chosen based on the situation. Keep cuts small (2x4"), use a hand saw or better, a rock knife, not power tools in drywall, cut only in highest-mold-risk locations.
• If you are in a seriously moldy area, wear a HEPA respirator. Repeated exposure toallergens can cause you to become sensitized even if you have not had problems in the past.
• If appropriate, keep spectators calm by explaining that you wear the mask because you're entering buildings every day. But keep their noses out of themold too. People who are at particular risk can get sick from a single exposure. (Examples: elderly, babies, people with compromised immune system.)
• Other risks may be present, related to the same conditions which caused mold growth: Sewer backups - bacterial hazards; wet areas, damaged electrical orother mechanical components, even shock hazards. If a building occupant is likely to be electrocuted, burned in a fire, or to fall down the stairs, those immediate hazards, noted in passing, must be pointed out and documented.

An Owner's Guide to Inspecting Homes and Other Buildings for Mold

Any experienced home inspector can identify conditions that riskwater entry or high moisture levels in a house. These conditions promote thegrowth of mold spores. Mold is a natural organism and it's virtually everywhere. The goal of "zero" mold spores makes no sense. But if conditions promote mold growth problems are more likely.

• Just because you don't see water stains, don't assume there was never a flood or a leak.
• If a building has had flooding, plumbing leaks, roof leaks, A/C condensate leaks, hidden mold may be at serious levels.
• Check HVAC equipment and duct work for presence of mold or other allergens. Pay close attention to duct work downstream from air filters and blowers; check blower compartments and duct work for contamination (including dead mice), and check other areas where condensate may have accumulated in duct lines, supporting mold growth. Clean ducts in one area don't assure clean ducts everywhere; a "clean" air test does *not* guarantee no ductcontamination either as variations in temperature, moisture, and mechanical disturbance can suddenly release mold spores into the building air.
• Just because you don't see mold, don't assume a severe mold infection can't be present (behind walls, under carpets, under insulation, in HVAC equipment.) I've found serious toxic mold colonies in walls which showed no external moisture stains nor external mold growth - the clue was other evidence of a history of leaks into the subfloor, confirmed by an impaction air sampler result. A large harmful mold reservoir may be inside fiberglass insulation that looks clean.
• Mold may or may not be present at problem-levels in house air even when a significant amount of mold contamination is present, depending on variations in humidity, temperature, season, air movement, and physical activity. Not finding it at a given moment is not an excuse for visual and in some cases invasive inspecting.
• A home inspection for mold is not a broad-spectrum environmental check for unhealthy mold or other bioaerosols orallergens. But if you see moldy conditions, warn your client.
• Do not assert that a specific illness or complaint is caused by mold. The four tests (proposed by Burge, Harvard School of Public Health) are stringent beyond your means as an inspector. Mold at high levels may cause and almost certainly aggravates or contributes to a wide variety of complaints.

A Building Owner's Guide to Valid Field and Lab Procedures for Mold

While anyone with proper training, a good eye for detail, and a little building science education should be able to recognize the presence of "mold," it takes a trained expert to identify even the most common of the mold. I've attended a number of classes, schools, workshops to learn field and lab procedures for years and still I can by no means identify all of these species. Nor can any of the other more expert sources with whom I consult.

About 80,000 mold species have been identified and named. About 1,500,000 additional species are not yet identified. Luckily not all 1.5 million species grow in buildings. I estimate that there are about 200 most-common molds that are able to grow in indoor conditions.

• A visual inspection by an expert is absolutely essential. There is a useful place for these test tools, but the fundamental and first method for inspection must include a visual inspection of the property to identify likely problem areas, combined with bulk or surface sampling of visible colonies or other potential contaminants.
• Settled dust sampling can give a useful clue about the history of presence of harmful particles including mold.
  
  See TAPE & BULK SAMPLING & TESTS for MOLD
• Where a visual inspection does not find visible mold there may be significant hidden mold reservoirs. Follow the water, march to the moisture and lead to the leak history of the building. A single-event that wet building cavities can leave behind a large mold reservoir in walls, behind paneling, in ceilings, under carpeting, in HVAC ductwork.
  
  See FALSE NEGATIVE MOLD TEST RESULTS
• Mold culture test kits are unreliable: Field test kits (petri dish left in house) are being sold by the same folks who hopped on the other Environmental Scare Bandwagons, as well as by some other labs. Finding mold this way might mean something, especially at high counts. Ninety percent of mold genera/species will not grow on any culture whatsoever. So you're 90% "wrong" in your mold test results when you remove the culture plate lid. What grows on culture may not represent what is a problem in the building.
  
  See MOLD CULTURE TEST KIT VALIDITY
• Air testing can give a false "clean house" indication: air tests, especially passive air tests, for mold are not reliable when used alone, and reliance on air sampling for mold without a competent building inspection is rejected by experts. You might get a false positive (says mold is present at problem levels when it's not) but youwill definitely risk false negatives (says mold is not present at problem levels when it is). Illnesses result from breathing mold spores butalso complaints are associated with ketones given off by mold colonies evenwhen no spores are detected.
  
  See ACCURACY OF AIR TESTS for MOLD
• Swab tests and other tests which rely on culturing are also not reliable as an overall characterization of what bioaerosols are present in a property. Deadspores may still be toxic; non-viable biological materials such as mouse dander won't grow in culture but may be a problem for house occupants as may be bacteria, pollen, animal hair (FIBER & HAIR IDENTIFICATION), mite fecal pellets, cockroach fecal pellets, etc. What grows on a culture is what likes to growon that individual media, not necessarily what's the most serious problem in the house.
  
  See SWAB & PCR SAMPLING & TESTS for MOLD
• Beware of bogus or semi-bogus or trouble-making "mold test tools" such as thermography or IR scanners, moisture meters, and ozone generators. It is correct that moisture is a necessary factor for mold growth on or in buildings, but a problem mold reservoir may be present in a building ceiling or wall that is dry at the time of inspection and thus does not appear in moisture or temperature scans that otherwise are great for finding air leaks and water.
  
  See THERMAL IMAGING MOLD SCANS
  and
  See OZONE MOLD / ODOR TREATMENT WARNINGS
• Remember to keep alert for other more immediate hazards: I found a wet moldy basement which had as a root cause a blocked gas-fired-appliance chimney which risked killing everyone in the building with carbon monoxide - a moreserious risk than mold in that instance.
  
  See BUILDING SAFETY HAZARDS GUIDE
  and
  See HOME & BUILDING INSPECTION SAFETY HAZARDS

How Much Mold is a Problem?

• If you see more than 30 sq.ft. of contiguous mold or mold-contaminated surface present in a building, the mold contamination should be cleaned up by a professional (read "expensive")
• Smaller amounts or areas of mold contaminated surfaces can be remedied by a homeowner or cleanup contractor. But during the cleanup the workers must be alert for the discovery of a larger, previously un-recognized mold reservoir.
• Some occupants who are sensitized may respond to very low levels of mold spores (orother allergens). I've conducted tests which proved that a client who was hypersensitive to airborne allergens responded to airborne mold at levels far below commonly accepted levels of indication of mold contamination. So don't assume that everyone will be equally happy with moldy walls. A general rule of thumb is that if mold is present indoors at significantly higher levels than outside, it's a problem and it is probably originating indoors.
• Some molds are cosmetic and do not need attention even if present over large areas of wood framing. Bluestain molds found on framing lumber are themselves not harmful.

What To Do About Mold: a Concise Summary of Critical Steps

• Mold Action Plan: What to Do About Mold in Buildings a simple step by step procedure for building owners and occupants as well as links to the New York mold remediation guidelines and to other mold cleanup standards are
  at MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
• Small surface areass of mold such as on ceramic tile, hardwood floor surfaces, windows, can be cleaned with a any household cleaner or dilute bleach solution (watch your eyes!)
• Not all mold needs to be tested: For many situations, expert field and lab analysis are not appropriate. Clean up the mold, fix the conditions that caused it, and clean your gutters.
• For larger areas of mold contamination, removal of moldy material and disinfect ion of surfaces is required.
• People at extra health risk should be out of the building during cleanup. (Elderly, infant, allergic, asthmatic, immune-impaired, etc.)
• People who have health complaints should first see their doctor, not their home inspector.
• Where a health complaint exists (respiratory, neurological, immune system) which makes people suspect the house ("I get better when I leave.") andwhere no obvious bioaerosol or allergen or mold is present, an expert might be needed to investigate.
• Whoever is doing mold cleanup needs to be alert for the discovery, as demolition progresses, of more serious amounts or types of mold. If necessary, work needs to stop for further testing and possibly for setup of containment measures.
• Mold cleaning job shortcuts are unreliable and may multiply the ultimate cost. Remove the moldy materials that can't be cleaned such as drywall, insulation, carpeting; clean hard surfaces. Do not rely on sprays as a substitute for proper cleaning, though there are appropriate uses for these treatments and coatings.
  
  See MOLD SANITIZER, SPRAY, BIOCIDE USE GUIDE

Mold Inspection Articles

• MOLD INSPECTORS & MOLD TESTERS
  • CHOOSE a FLOOD DAMAGE RESTORATION or MOLD REMEDIATOR
  • CONFLICTS OF INTEREST
  • MOLD INSPECTION HOME BUYERS GUIDE
  • MOLD INSPECTION SERVICE
• MOLD INVESTIGATION PROCEDURE TIPS
  • FIND MOLD, ESSENTIAL STEPS
  • HOME BUYERS or OCCUPANTS GUIDE to EVIRONMENTAL or MOLD TESTS
  • LIGHT, GUIDE to FORENSIC USE
  • THERMAL IMAGING MOLD SCANS
  • TRAPPED MOLD BETWEEN WOOD SURFACES
  • UV LIGHT BLACK LIGHT USES
• MOLD INVESTIGATION REPORTS

Daniel Friedman is a licensed and certified home inspector, areobiologist, forensic microscopist, and sick building investigator who has worked in these fields since 1978. - Presentation Updated 2015/09/15; original presentation 10 Jan 01 at the World Inspection Network Conference, Phoenix AZ, and for 6 December 01 for the NY Metro ASHI News - Metropolitan New York chapter of ASHI, the American Society of Home Inspectors. The page top photograph shows Craig Balchunas, a New York home inspector (now retired), examining a building for mold.

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• FIND MOLD, ESSENTIAL STEPS
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