Resource Hub · Reference
The Restoration Glossary
57+ water, fire, and mold restoration terms in plain English — for the technicians, estimators, adjusters, and property owners who use them every day. Written and maintained by the team at DRR.
Water Damage Categories & Classes
How the industry classifies water losses — the first thing that determines scope, PPE, and the claim.
- Category 1 Water
- Water from a sanitary source — a broken supply line, a tub overflow, rainwater — that poses no substantial health risk at the moment of release. Left untreated, it degrades to Category 2 or 3 over hours to days.
- Category 2 Water (Gray Water)
- Water carrying significant contamination that could cause illness or discomfort if contacted — washing-machine or dishwasher discharge, toilet overflow containing urine but no feces, or aged Category 1 water.
- Category 3 Water (Black Water)
- Grossly contaminated water that may contain pathogens, toxins, or other harmful agents — sewage, ground-surface flooding, rising rivers, or toilet overflow containing feces. Requires the highest level of PPE and containment.
- Drying Class 1
- The least amount of water and the smallest evaporation load — minimal absorption into low-porosity materials, affecting only part of a room.
- Drying Class 2
- A large amount of water affecting an entire room, with moisture wicked up walls less than about 24 inches and absorbed into carpet, cushion, and structural materials.
- Drying Class 3
- The greatest evaporation load — water that has come from overhead, saturating ceilings, walls, insulation, and subfloors throughout the space.
- Drying Class 4
- Specialty drying for deeply held or bound water in low-evaporation materials such as hardwood, plaster, concrete, and stone, which require longer drying times and specialized methods.
- Migration
- The movement of water through building materials and cavities away from its source — why the visibly wet area is rarely the full extent of a loss.
- Wicking
- Capillary movement of water upward into porous materials such as drywall and carpet pad, often carrying contamination with it.
Drying Science & Psychrometry
The physics behind structural drying — the numbers a technician tracks every day on the job.
- Psychrometry
- The study of the relationship between air, temperature, and moisture. It is the science that governs structural drying — controlling these variables is how a restorer removes water from a building.
- Relative Humidity (RH)
- The amount of moisture in the air expressed as a percentage of the maximum that air can hold at its current temperature. RH alone can mislead, because warmer air holds more water.
- Grains Per Pound (GPP)
- The actual weight of water vapor in the air, measured in grains per pound of dry air (7,000 grains equal one pound). GPP is the truest, temperature-independent measure of how much moisture air is carrying.
- Dew Point
- The temperature at which air becomes fully saturated and water vapor begins condensing into liquid. Keeping surfaces above the dew point prevents secondary condensation damage.
- Vapor Pressure
- The share of air pressure exerted by water vapor. Drying occurs when vapor pressure inside wet materials is higher than in the surrounding air, pushing moisture out.
- Specific Humidity
- The mass of water vapor per unit mass of dry air — closely related to GPP and used to measure true moisture content independent of temperature swings.
- Evaporation
- The phase change of water from liquid to vapor. Accelerating evaporation with airflow and heat, then capturing the vapor with dehumidification, is the core of the drying process.
- Equilibrium Moisture Content (EMC)
- The moisture level at which a material is in balance with the surrounding air and neither gains nor loses moisture. Often used to define the drying goal.
- Drying Goal
- The target moisture content that defines a material as 'dry' — typically benchmarked against an unaffected reference area in the same structure rather than an arbitrary number.
Equipment
The machines that do the work — and what makes them different.
- Air Mover
- A high-velocity fan that sweeps air across wet surfaces to accelerate evaporation. Correct placement and count — not just quantity — determine drying speed.
- LGR Dehumidifier
- A Low-Grain Refrigerant dehumidifier engineered to pull moisture out of air that is already relatively dry. It is the workhorse of modern structural drying because it keeps working at low grain depressions where standard units stall.
- Refrigerant Dehumidifier
- A dehumidifier that removes moisture by condensing it on cold coils. Effective in warm, humid conditions but loses efficiency as the air dries out.
- Desiccant Dehumidifier
- A dehumidifier that adsorbs moisture onto a desiccant material such as silica gel. It excels in cold or very-low-humidity environments where refrigerant units struggle, and on Class 4 bound-water losses.
- HEPA Filter
- A High-Efficiency Particulate Air filter that captures at least 99.97% of particles at 0.3 microns — the size hardest to trap. Required for mold and biohazard air filtration.
- Air Scrubber (AFD)
- An Air Filtration Device that draws air through HEPA filtration to remove airborne particles and can establish pressure differentials within a work area.
- Negative Air Machine (NAM)
- An air scrubber configured to exhaust filtered air outside a containment, creating negative pressure so contaminants flow inward and cannot escape into clean areas.
- Air Changes Per Hour (ACH)
- How many times the entire volume of air in a space is filtered or replaced in one hour. ACH targets drive how much air-scrubbing capacity a containment needs.
- Moisture Meter
- An instrument that measures the moisture content of materials. Pin meters read invasively at depth; pinless meters scan beneath the surface without holes.
- Thermo-Hygrometer
- A meter that reads temperature and relative humidity, which together let a technician calculate GPP and chart drying progress day over day.
- Thermal Imaging Camera
- A camera that visualizes surface-temperature differences. Because evaporating moisture cools a surface, it helps locate hidden water behind walls and under floors — though it detects temperature, not moisture itself.
Mold
Terms from the IICRC S520 world of mold remediation.
- Remediation vs. Removal
- Remediation returns the mold in a structure to a normal, natural level (Condition 1). Total 'removal' of all mold is neither achievable nor the goal — a claim of 100% removal is a red flag.
- Condition 1 / 2 / 3
- A way to describe a space's fungal status: Condition 1 is a normal ecology; Condition 2 is settled spores or fragments that drifted from a growth area; Condition 3 is actual active mold growth.
- Containment
- Physical barriers combined with controlled air pressure that isolate a work area so spores and debris cannot spread to clean parts of the building during remediation.
- Stachybotrys chartarum
- A greenish-black mold commonly called 'black mold,' typically found on chronically wet cellulose materials such as drywall paper. Identification and removal follow remediation protocol regardless of species.
Fire & Smoke
Terms from fire, soot, and odor restoration (IICRC S700).
- Soot
- Fine carbon residue produced by incomplete combustion. It is acidic and corrosive, which is why prompt cleaning protects metals, electronics, and finishes from permanent etching.
- Wet Smoke vs. Dry Smoke
- Wet smoke comes from low-heat, smoldering fires and leaves sticky, smeary, strong-odor residue. Dry smoke comes from fast, high-heat fires and leaves a dry, powdery residue. Each requires different cleaning methods.
- Thermal Fogging
- A deodorization method that uses a heated fog to penetrate the same porous materials smoke reached, neutralizing trapped odor molecules.
- Hydroxyl vs. Ozone
- Two odor-neutralizing technologies. Ozone is powerful but must run in unoccupied spaces; hydroxyl generators are gentler and can operate safely with people and contents present.
Biohazard & Sewage
Category 3 and trauma cleanup terms governed by OSHA and IICRC S540.
- Bloodborne Pathogens
- Infectious microorganisms carried in human blood and bodily fluids. Cleanup involving them is governed by the OSHA Bloodborne Pathogens standard (29 CFR 1910.1030).
- PPE
- Personal Protective Equipment — respirators, suits, gloves, and eye protection — selected to match the hazard level of the specific loss, escalating with water category and biohazard risk.
- Regulated Waste
- Contaminated materials that must be containerized, labeled, transported, and disposed of according to federal, state, and local rules rather than placed in ordinary trash.
Insurance & Estimating
The claims-and-money vocabulary every restorer and adjuster shares.
- Xactimate
- The estimating platform most widely used by insurers and restoration contractors to scope, price, and document property claims using standardized line items and regional pricing.
- Replacement Cost Value (RCV)
- The cost to repair or replace damaged property with new materials of like kind and quality, without any deduction for age or wear.
- Actual Cash Value (ACV)
- Replacement Cost Value minus depreciation — what many policies pay out initially before repairs are completed.
- Recoverable Depreciation
- The portion of value withheld as depreciation that the policyholder can recover once the repair work is actually completed and documented.
- Supplement
- An addition to an approved estimate covering work, materials, or hidden damage discovered after the original scope was written.
- Deductible
- The set amount a policyholder pays out of pocket on a claim before insurance coverage begins to contribute.
- Mitigation
- The emergency phase of a loss — extraction, drying, and board-up — that stops further damage. It is distinct from, and precedes, repairs and reconstruction.
- Line Item
- A single priced task or material within an estimate. Accurate, defensible line items are how a scope survives an adjuster's review.
- Scope of Work
- The documented list of everything that will be done on a project — the agreed map of the job that drives the estimate and the schedule.
Standards & Credentials
The bodies, standards, and certifications that define professional restoration.
- IICRC
- The Institute of Inspection, Cleaning and Restoration Certification — the organization that develops the ANSI-approved consensus standards and certifies restoration technicians and firms.
- IICRC S500
- The ANSI/IICRC consensus standard for professional water damage restoration — the recognized standard of care for water losses.
- IICRC S520
- The ANSI/IICRC consensus standard for professional mold remediation, defining conditions, containment, and clearance expectations.
- IICRC S700
- The ANSI/IICRC consensus standard for professional fire and smoke damage restoration — first published in 2024, making it the newest of the core standards.
- Standard of Care
- The level of skill and diligence a reasonably prudent restoration professional would apply under similar circumstances — the benchmark used to judge whether work was done properly.
- ICRA
- Infection Control Risk Assessment — the framework for planning and containing restoration or construction work inside occupied healthcare facilities.
- HAZWOPER
- Hazardous Waste Operations and Emergency Response — the OSHA training program required for workers handling hazardous materials.
- Antimicrobial
- An EPA-registered product applied to surfaces to inhibit the growth of bacteria, mold, and other microorganisms. It must be used strictly per its label.
These definitions are original, plain-English explanations written for education and quick reference. Where an IICRC standard (S500, S520, S700) or an OSHA regulation is named, it is cited for reference only — consult the published standards and regulations themselves for authoritative, complete requirements. This glossary is not a substitute for professional training, certification, or the applicable standard of care.