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Reference

Glossary

Plain-English definitions of the terms used in mold reports, protocols and the Texas rules.

Legal definitions, word for word: 16 TAC §78.10 (49 definitions) Occupations Code §1958.001 EPA guide, Appendix A Explained in plain English

A

Actual growth: Mold that has colonized a material and formed mycelia, growth structures and spores, whether active or dormant, visible or hidden. This is what the S520 calls Condition 3. Based on ANSI/IICRC S520 (2024), p. 14.
Affected area: The part of a building damaged by water, either directly or by what followed (for example, humidity or mold). Based on IICRC S500 (2021), p. 15.
Air filtration device (AFD): A fan, filters and housing that pull air through a HEPA filter to strip out airborne particles; also called an air scrubber or negative air machine. Based on IICRC S500 (2021), p. 15.
Air sample: A measured volume of air pulled through a collector so a lab can count and identify spores. Compared with an outdoor sample taken at the same time.
Airlock (decontamination chamber): An enclosed space at the entry of full containment where workers remove and bag protective clothing before leaving.
Airmover: A fan designed to push air across wet surfaces to speed drying in water-damage restoration. Based on IICRC S500 (2021), p. 15.

B

Back-drafting: Exhaust from a gas water heater or furnace being pulled back into the house, a carbon monoxide hazard; it can happen when drying equipment depressurizes a space too much. Based on IICRC S500 (2021), p. 67.
Biocide: A chemical that kills living organisms, including mold. Not a substitute for removing mold.
Bound water: Moisture held inside a material's structure that doesn't need to be dried out — some is normal in wood and concrete. Based on IICRC S500 (2021), p. 15.

C

Category of water (1, 2, 3): How contaminated water is: 1 sanitary, 2 significantly contaminated, 3 grossly contaminated (sewage, flood, seawater). See the topic. Based on IICRC S500 (2021), pp. 15–16.
Certificate of Mold Damage Remediation (CMDR): The Texas certificate a property owner receives after a licensed remediation passes clearance. Sellers must pass on certificates from the last five years.
Change order: A written change to the contract when the scope of work changes mid-job; undocumented changes are a common source of disputes. It should set out the change, timing, price and payment, and be accepted in writing by both sides. Based on IICRC S500 (2021), pp. 40, 54.
Class of water intrusion (1–4): How big the drying job is, by the share of wet surface area and how slowly materials dry. See the topic. Based on IICRC S500 (2021), p. 16.
Clearance: The post-remediation evaluation that decides whether a job is finished. In Texas, performed by a licensed Mold Assessment Consultant.
Clearance criteria: The standards — visual and numeric — set in the protocol before work begins that a remediated area must meet to pass.
Condensation: Water that forms when humid air touches a surface colder than its dew point — on AC ducts, cold-water pipes, windows.
Condition 1, 2 and 3: The S520's three states of an indoor space. Condition 1 is "normal fungal ecology," the background level of spores in a clean, dry building. Condition 2 is a space contaminated with settled spores, fragments and other residue from a Condition 3 source nearby. Condition 3 is actual mold growth, "active, dormant, dead, non-viable, visible, or hidden." Only an IEP can assess Condition; without one, a contractor may assume it if they disclose that to the client. Texas law uses its own terms, not these. ANSI/IICRC S520 (2024), p. 14.
Constant and falling drying rate stages: Drying runs fast and steady while the surface stays wet (constant rate), then slows as less water reaches the surface (falling rate). Fast airflow matters most in the first stage. Based on IICRC S500 (2021), p. 66.
Containment: A plastic enclosure, usually under negative pressure, that keeps spores and dust inside the work area.
Containment (water damage): Barriers — usually 6-mil plastic sheeting, often with pressure differences — that wall off an area for drying or keep contamination from spreading. Based on IICRC S500 (2021), p. 17.
Contamination: Substances that don't belong in a normal indoor environment in that kind, place or amount, and that can harm health, the structure, contents or building systems. Based on IICRC S500 (2021), p. 17.
Contents: In water-damage restoration, personal property and fixtures that aren't part of the building plans — furniture, appliances, electronics, clothing, food and so on. Based on IICRC S500 (2021), p. 75.
Contiguous: In close proximity; neighboring (16 TAC §78.10). Texas measures mold by contiguous area: 25 contiguous square feet is the licensing line for remediation.
Critical barrier: Plastic sheeting (such as 6-mil polyethylene) or similar material that seals openings like vents, doors and penetrations inside a containment, so air and spores can't move in or out. Based on ANSI/IICRC S520 (2024), p. 15.
Cross-contamination: Contaminants spreading from a dirty area into a clean one. Based on IICRC S500 (2021), p. 17.

D

Decontamination: Removing contaminants that have built up on workers and equipment. The S520 says all people, clothing, equipment and materials leaving the contaminated area should be decontaminated. Based on ANSI/IICRC S520 (2024), p. 15.
Dehumidification: Taking moisture out of the air. Based on IICRC S500 (2021), p. 17.
Dew point: The temperature at which air can't hold its water vapor and condensation forms.
Discovery rule: In many places, the time limit for a legal claim starts when the problem is discovered, not when the work was done — one reason restorers keep job records for a long time. Based on IICRC S500 (2021), p. 43.
Disinfectant: A product that kills disease-causing microorganisms on surfaces (not necessarily their spores). Disinfecting is not the same as removing mold. Based on IICRC S500 (2021), p. 17.
Drying environment (drying chamber): An area closed off by walls or temporary barriers where drying is sped up; one job can have several, each with its own category and class. Based on IICRC S500 (2021), p. 18.
Drying plan and drying goal: The restorer's plan for controlling humidity, temperature and airflow, and the target moisture level each material must reach — normally its dry standard, the moisture it had before the water event. Based on IICRC S500 (2021), pp. 17–18.
Dust control: Suppressing, capturing or removing dust from surfaces or air, by vacuuming, filtration, wiping, or barriers like plastic sheet. The S520 treats dust in or near a remediation area as Condition 2 contamination, so thorough dust removal removes much of it. Based on ANSI/IICRC S520 (2024), p. 16.

E

Encapsulant: A coating or sealant applied over a contaminant to seal it in. The S520's rule for mold is direct: mold contamination "should be removed and should not be encapsulated in lieu of cleaning." Mold-resistant coatings are for after removal. ANSI/IICRC S520 (2024), p. 16.
Engineering controls: Equipment and containment used to limit workers' and occupants' exposure and keep contaminants from spreading to clean areas. Based on ANSI/IICRC S520 (2024), p. 16.
Equilibrium moisture content (EMC): The moisture content at which a material stops gaining or losing water in air of a given temperature and humidity. Based on IICRC S500 (2021), p. 18.
Evaporation load: How much water vapor wet materials will add to a drying area; it drives how much drying equipment a job needs. Based on IICRC S500 (2021), p. 18.
Extracellular material (ECM): Substances molds release as they grow, including mVOCs, mycotoxins, allergens and irritants. Except for mVOCs, they cling to spores and fragments and come out with the dust and debris during remediation. Based on ANSI/IICRC S520 (2024), p. 16.

F

Fogging and misting: Spraying fine droplets into the air to knock down dust and spores so they can be cleaned up. Fog droplets are under 50 microns; mist droplets are larger. In the S520 these are dust-control methods, not a substitute for removing mold. Based on ANSI/IICRC S520 (2024), pp. 16–18.
Free water: Liquid water on a surface and in a material's pores, beyond what the material holds internally; all of it has to be removed in drying. Based on IICRC S500 (2021), p. 18.
Fungicidal coating: An EPA-registered antimicrobial paint-like coating applied to surfaces that have already been cleaned, to slow future growth. The S520 says it should not be used to cover over mold growth. Based on ANSI/IICRC S520 (2024), p. 17.

G

General Duty Clause: The part of the federal OSH Act requiring every employer to keep the workplace free of recognized hazards likely to cause death or serious physical harm. Cited in IICRC S500 (2021), pp. 31–32.
Glucans: Pieces of mold cell walls that can inflame the lungs and airways.

H

Health issues (S520): Concern, complaint or risk of mold-related health effects, including for sensitized and immunocompromised people. The S520 lists allergy, irritation, inflammation, toxicosis and infection as the typical effects. Based on ANSI/IICRC S520 (2024), p. 17.
HEPA: High-efficiency particulate air filter: one that removes at least 99.97% of particles at 0.3 microns, the hardest size to catch, and does better on larger and smaller ones, including mold spores (ANSI/IICRC S520 (2024), p. 17). Used in vacuums and air-filtration units.
HEPA vacuum: A vacuum with a HEPA filter as its last stage, built so that all the air it pulls in leaves through that filter with none leaking past it. Based on ANSI/IICRC S520 (2024), p. 17.
Hidden mold: Growth behind walls, under flooring, above ceilings or inside HVAC equipment, out of sight.
Humidity control: Removing water vapor from the air at least as fast as wet materials release it, to limit moisture migration, secondary damage and microbial growth. Based on IICRC S500 (2021), p. 18.
Humidity ratio (grains per pound): The weight of water vapor per weight of dry air, often given in grains per pound; restorers use it to track whether drying is working. Based on IICRC S500 (2021), p. 18.
Hypersensitivity pneumonitis: An uncommon lung disease from repeated exposure to mold or other organic dust that resembles pneumonia.
Hyphae: The microscopic filaments a mold grows; a mass of them is called a mycelium. Based on ANSI/IICRC S520 (2024), p. 17.

I

IDLH: Immediately dangerous to life or health: air so hazardous (or so low in oxygen) that air-purifying respirators may not be used; only supplied air such as SCBA. Based on IICRC S500 (2021), p. 33.
IICRC: Institute of Inspection, Cleaning and Restoration Certification. Publishes the S520 mold remediation standard and R520 reference guide.
Immunocompromised individual: Someone at higher risk of illness because their immune system isn't working normally. The S520's examples include pregnant women, young children, the elderly, people with underlying illness and people recovering from surgery. Based on ANSI/IICRC S520 (2024), p. 18.
Indoor environmental professional (IEP): In IICRC standards, the person who assesses contamination, plans sampling and interprets results. In Texas, that role on a regulated mold project belongs to a licensed Mold Assessment Consultant. Based on IICRC S500 (2021), p. 18. The S520 adds that the IEP determines Condition 1, 2 or 3 to set the scope of work and to verify the site is back to Condition 1 (ANSI/IICRC S520 (2024), p. 18).
Inspection (water damage): Gathering the information needed to decide the category, condition and class of a water loss and the state of the materials and systems involved. Based on IICRC S500 (2021), p. 19.

K

Knockdown: Using fog or mist to make airborne particles heavy enough to settle. The settled residue still has to be physically cleaned up. Based on ANSI/IICRC S520 (2024), p. 18.

L

Limitation, complexity, complication, conflict: The S500's four kinds of job problems: a restriction the owner places on the work; something that makes the job harder but still doable; something found after work starts that changes the scope; and a disagreement about how the work should be done. Based on IICRC S500 (2021), pp. 53–54.
Low evaporation materials and assemblies: Materials that take in and give up water slowly — plaster, wood, concrete, masonry — and layered assemblies like multilayer drywall, subfloors and gym floors. They are what makes a job Class 4. Based on IICRC S500 (2021), p. 19.

M

MAC (Mold Assessment Consultant): The Texas license for assessors who perform assessments, write remediation protocols and perform clearance.
Materially interested parties: Anyone substantially and directly affected by a mold job, such as the owner, occupants, insurer or contractor. Based on ANSI/IICRC S520 (2024), p. 18.
MERV: Minimum Efficiency Reporting Value — a filter rating. EPA suggests at least MERV 8 for systems serving a remediation area.
Mildew, yeasts, mushrooms and slime molds: Words often mixed up with mold. The S520 notes that "mildew" is commonly used for mold growth or its smell, but calling it mildew doesn't change how it should be handled. Yeasts and mushrooms are fungi but not molds, and slime molds aren't fungi at all. Based on ANSI/IICRC S520 (2024), p. 19.
Mitigation: Limiting further damage by controlling the spread of water and contamination — the emergency first stage of a water job. Based on IICRC S500 (2021), p. 19.
Moisture content vs. moisture level: Moisture content is a percentage of a material's dry weight, measured with a meter calibrated for that material. Moisture level is a relative reading from a meter that isn't calibrated for it — useful for comparison, not as a true percentage. Based on IICRC S500 (2021), p. 19.
Moisture map: A drawing or record showing how far water spread through the building, including the dry areas next to the wet ones. Based on IICRC S500 (2021), p. 19.
Moisture meter: A probe or contact meter that measures moisture in drywall, wood, carpet or concrete.
Moisture meter and moisture sensor: A moisture meter gives a numerical reading of a material's moisture; a moisture sensor only signals that moisture is probably present. Based on IICRC S500 (2021), p. 19.
Mold: Fungi that grow on surfaces and materials. Texas law defines it as living or dead fungi or related products or parts, including spores and hyphae.
Mold assessment: In Texas: inspecting a building for mold, developing a protocol or management plan, or collecting or analyzing a mold sample.
Mold remediation: In Texas: removing, cleaning, sanitizing, demolishing or otherwise treating mold or mold-contaminated matter that wasn't purposely grown there, including preventive treatment.
Mold-resistant coating: A paint-like coating with an EPA-registered antimicrobial that inhibits growth on or in the film. It doesn't kill or disinfect, and the S520 says it should be used after mold is removed, never as a cover over growth. Based on ANSI/IICRC S520 (2024), p. 19.
Monitoring (drying): Recording moisture, temperature and humidity readings over time to show that drying is progressing. Based on IICRC S500 (2021), p. 19.
MRC (Mold Remediation Contractor): The Texas license for those who run remediation projects and write work plans.
mVOC: Microbial volatile organic compound: gases released by growing mold and bacteria, and the source of the musty smell. The S520 notes they are not mycotoxins, and their confirmed health effects are eye, upper-airway and sensory irritation (ANSI/IICRC S520 (2024), p. 18).
Mycelium: The visible mass of branching filaments (hyphae) that makes up a mold colony. Based on ANSI/IICRC S520 (2024), p. 19.
Mycotoxin: A toxic compound some molds can produce under certain conditions; mold present doesn't mean mycotoxins present. The S520 counts over 300 identified mycotoxins, notes they are not mVOCs and don't behave as a gas, and says they are removed by the same physical remediation used for mold growth and contaminated dust. It adds that no chemical process on its own (enzymes, UV, ionization, oxidation) is known to destroy them all (ANSI/IICRC S520 (2024), p. 19).

N

N-95: A disposable respirator that filters 95% of airborne particles. The minimum respiratory protection for mold work.
NADCA ACR: The National Air Duct Cleaners Association's standard for assessing, cleaning and restoring HVAC systems, including how clean a system must be and how to inspect it. Referenced in IICRC S500 (2021), p. 73.
Negative pressure: Lower air pressure inside containment than outside, so air leaks in rather than out.

O

ODTS (Organic Dust Toxic Syndrome): A flu-like illness from very high exposure to mold dust or glucans, noted mainly in farm and manufacturing work.
Open, closed and combination drying systems: Three ways to dry a building: open uses drier outdoor air without dehumidifiers; closed seals the area and runs dehumidifiers; combination does both, often venting early and closing up later. Based on IICRC S500 (2021), p. 67.

P

PAPR: Powered air-purifying respirator: a blower pushes air through a HEPA filter into a mask or hood.
Permit-required confined space: Under OSHA, a confined space with added dangers — such as a hazardous atmosphere or material that could engulf someone — that needs a written entry permit and program. Crawlspaces can qualify. Based on IICRC S500 (2021), p. 35.
Physical removal: Taking mold off a surface by wiping, brushing, sanding, grinding, blasting, HEPA vacuuming or removing the material. As the S520 puts it, "simply applying a chemical is not physical removal." ANSI/IICRC S520 (2024), p. 20.
Plenum: Space that carries heating or cooling air, such as above a drop ceiling or under a raised floor. Based on ANSI/IICRC S520 (2024), p. 20.
Pockets of saturation: Hidden areas of trapped water — inside walls, under stairs, flooring and built-ins — that have to be opened up to dry or remove. Based on IICRC S500 (2021), p. 62.
Porous, semi-porous and non-porous: How readily a material takes in water: porous items (textiles, upholstery, paper, leather) soak it up fast; semi-porous ones (unfinished wood, concrete, brick, OSB) slowly but can grow mold; non-porous ones (glass, metal, plastic, finished wood) barely at all. Based on IICRC S500 (2021), p. 75. For mold, the S520 adds that non-porous surfaces can be cleaned of Condition 2 or 3, porous ones generally can't be cleaned of actual growth (Condition 3), and semi-porous ones are judged case by case (ANSI/IICRC S520 (2024), p. 20).
Post-remediation evaluation: The check after a contaminated-water cleanup that surfaces are visibly free of dust and debris and odors are gone; independently verified by an IEP when the risk is higher. Based on IICRC S500 (2021), p. 64.
Post-remediation evaluation vs. verification: In IICRC terms, the evaluation is the remediator's own check after the work; verification is done by an independent IEP. In Texas, clearance on a regulated mold project is a licensed Mold Assessment Consultant's post-remediation assessment. Based on IICRC S500 (2021), p. 19.
Post-remediation verification: An inspection and assessment by an independent, third-party IEP after the work, which may include sampling, to verify the area is back to Condition 1. The S520 says the remediator's own post-remediation evaluation is not the same thing. Based on ANSI/IICRC S520 (2024), p. 20.
PPE: Personal protective equipment: respirator, gloves, goggles, coveralls.
Pre-remediation and pre-restoration evaluation: The restorer's review of what the inspection found — where the water went, what may be contaminated, and which specialists are needed — used to build the work plan, drying plan and safety plan. Based on IICRC S500 (2021), p. 20.
Preliminary determination: The restorer's first call on what category of water a job involves, used to set the scope of work. Based on IICRC S500 (2021), p. 20.
Preliminary determination: The restorer's first conclusions from the initial inspection: where moisture got in, where mold is or may be growing, and whether other experts are needed. Based on ANSI/IICRC S520 (2024), p. 20.
Preservation: Cleaning, drying or otherwise protecting items that can't be fully restored but are worth keeping for their monetary or sentimental value. Based on IICRC S500 (2021), p. 20.
Preserve: To stabilize an irreplaceable item that can't be returned to Condition 1 so it won't be further damaged by mold. Based on ANSI/IICRC S520 (2024), p. 20.
Primary, secondary and pre-existing damage: Primary damage comes from direct contact with the water; secondary damage follows indirectly (humidity, microbial growth, residue stains); pre-existing damage was there before this water event, like dry rot or old mold. Based on IICRC S500 (2021), p. 17.
Psychrometry: The science of air and water vapor mixtures — temperature, humidity, dew point — that drying calculations rely on. Based on IICRC S500 (2021), p. 20.

Q

Qualified laboratory: In the S520, a lab accredited under EMLAP, A2LA, NELAP or an equivalent program. In Texas, mold samples must also go to a TDLR-licensed lab. Based on ANSI/IICRC S520 (2024), p. 20.

R

Relative humidity (RH): How much water vapor the air holds compared with the most it could hold at that temperature. Keep indoors below 60%, ideally 30–50%.
Remediation protocol: The licensed Mold Assessment Consultant's written plan for a project: areas, estimated quantities, methods, PPE, containment and clearance criteria.
Remediation work plan (RWP): In the S520, the outline of a mold job's goals and tasks. In Texas the remediator's work plan has to follow the licensed assessor's protocol. Based on ANSI/IICRC S520 (2024), p. 21.
Restoration: Returning a damaged structure, systems or contents to their condition before the damage. Based on IICRC S500 (2021), p. 20.
Restorative drying: Controlled removal of excess moisture from a building and its materials until they reach the drying goal. Based on IICRC S500 (2021), p. 20.
RRP rule: EPA's Renovation, Repair and Painting rule for work that disturbs lead-based paint in homes built before 1978; it applies to restorers doing demolition. Based on IICRC S500 (2021), p. 35.

S

Safety data sheet (SDS): The manufacturer's sheet of hazards, handling and first aid for a chemical. On water-damage jobs, SDS for every chemical used are kept on site and given to the customer on request. Based on IICRC S500 (2021), p. 63.
Sanitizer: A product that reduces the number of microorganisms on a surface without killing all of them — a lower bar than a disinfectant. Based on IICRC S500 (2021), p. 20.
Scope of work: The itemized list of services to be performed on a restoration or remediation project. In Texas mold law, the consultant's protocol is also called a work analysis. Based on IICRC S500 (2021), p. 20.
Scope of work (SOW): The part of an agreement that describes the work; the S520 says it should include milestones, reports, deliverables and a timeline. Based on ANSI/IICRC S520 (2024), p. 21.
Sensitized individual: Someone more likely than most to react to mold, from predisposition or past exposure; some need spaces cleaner than normal. Based on ANSI/IICRC S520 (2024), p. 21.
Specialized expert: Someone with specific expertise a restoration job may need — an IEP, HVAC technician, art or document conservator, electrician and so on. Based on IICRC S500 (2021), p. 21.
Spore: The microscopic reproductive particle of a mold, present in all indoor and outdoor air. EPA gives the range as 2 to 100 micrometers; most common spores are toward the small end. The S520 notes that ordinary microscopy identifies spores only to genus, and that whether a given spore is viable can't be known unless it is given conditions to grow, which is how culture tests work (ANSI/IICRC S520 (2024), p. 21).
Sporulation: Mold releasing spores. Some spores, such as Alternaria, are light and can stay airborne for hours or days; others, such as Stachybotrys chartarum, are heavy and fall close to the growth. Based on ANSI/IICRC S520 (2024), p. 21.
Stachybotrys chartarum: A greenish-black mold that grows on very wet cellulose such as drywall paper. Often called “black mold”.
Stains (after remediation): Discoloration left after mold and debris are removed and the area has passed. The S520 treats fixing stains as cosmetic, not part of mold remediation. Based on ANSI/IICRC S520 (2024), p. 21.
Standard of care: What a reasonably prudent, competent member of the trade would normally do. Based on IICRC S500 (2021), p. 21.
Standard of care: What reasonably careful, qualified members of a trade commonly do. Based on ANSI/IICRC S520 (2024), p. 21.
Static pressure drop test: Measuring air pressure across an HVAC coil with a manometer or Magnehelic gauge, before and after cleaning, to show whether debris is really gone. Based on IICRC S500 (2021), p. 74.
Sublimation (vacuum freeze-drying): Drying frozen books, documents and electronic media in a vacuum chamber so the ice turns straight to vapor without melting. Based on IICRC S500 (2021), pp. 77, 81.

T

TDLR: Texas Department of Licensing and Regulation — licenses mold assessors and remediators and enforces 16 TAC Chapter 78.
Thermo-hygrometer: A meter that reads air temperature and relative humidity, and often calculates humidity ratio, vapor pressure and dew point. Based on IICRC S500 (2021), p. 21.
TMARR: Texas Mold Assessment and Remediation Rules — 16 TAC Chapter 78.

U

Unrestorable: Material that can't reasonably be saved — because it's structurally damaged, can't be cleaned or dried to goal, or would cost too much to restore. Based on IICRC S500 (2021), p. 21.

V

Vapor diffusion: Water vapor moving through a material, driven by a difference in vapor pressure from one side to the other. Based on IICRC S500 (2021), p. 21.

W

Water activity (aw): How much water on a surface is available for microbes to grow. It tracks the relative humidity right at the material's surface: 80% surface RH equals an aw of 0.8. Based on IICRC S500 (2021), p. 21.
Water vapor pressure (vapor pressure): The part of the air's total pressure that comes from water vapor; differences in it drive drying. Based on IICRC S500 (2021), p. 21.
Water-damaged building: A building where unwanted water or moisture has been present long enough to support microbial growth or damage materials, shown by things like high moisture readings, humidity, staining, swelling, odor or visible mold. Based on ANSI/IICRC S520 (2024), p. 22.
Work authorization: A signed form letting a company work on someone else's property; on a water-damage job it comes from the owner or their authorized agent before any work. Based on IICRC S500 (2021), p. 39.
Work plan: The Texas remediator's written instructions for carrying out the assessor's protocol, kept on the job site.