Reference

Glossary

What's the difference between mold risk and Mold IQ score: mold risk is the general likelihood of growth; the MoldRiskIQ score is this product's 0–100 number for one address.

Why these two terms are not interchangeable

Mold risk is a general idea: some buildings are likelier to grow mold than others, and you can reason about which without any product involved. The MoldRiskIQ score is a specific measurement of it — one model, one 0–100 scale, four named modules with published weights, applied to one address.

The distinction matters when comparing tools. Two products can both claim to assess mold risk and mean entirely different things: one may be reading climate data for a postal code, another may be modelling a specific building's envelope and its documented water history. Asking which modules a score contains, and what each is worth, is the question that separates them.

Scoring and this product

Building Vulnerability: The scoring module covering the structure itself: construction era, exterior materials, roof form, foundation and below-grade space. Worth 25 points. Its base figure comes from the construction era, adjusted by the specific materials and details known for that property.
data completeness: How much of the information a model wants was actually available for a property, reported separately from the score itself. A score of 55 on near-complete data and a score of 55 on three known facts are not the same claim, and collapsing them into one number hides the difference.
Disclosure and Event History: The scoring module covering what is on the record about this property: seller disclosure statements, documented water intrusion, and historical hazard events. Worth 45 points, the largest single module, because a documented past event is stronger evidence than any inference about a building's type.
evidence floor: A minimum score that observed conditions impose regardless of how favourable everything else is. A documented, unresolved water intrusion sets a floor, because no amount of good climate, terrain and construction makes an active leak safe.
evidence strength: How firmly a risk factor is established, which decides how much of its weight is applied. A factor confirmed by an inspection counts for a quarter more than one confirmed on paper; one inferred from the building's cohort counts for seven tenths; one merely suspected counts for four tenths.
moisture risk: The likelihood that liquid water or sustained high humidity reaches building materials and stays there long enough to matter. Mold is one consequence of moisture risk; rot, corrosion and material failure are others. Assessing moisture is the useful question because moisture is the variable a building owner can change.
mold risk scorealso: mold risk scoring, property mold risk score: An estimate of how favourable a property's conditions are to mold growth, produced from records about the building, its site and its water history rather than from anything sampled inside it. It describes probability of conditions, not presence of mold.
mold-favourable dayalso: mold favourable days, mold-favourable days: A day where the mean dew point reaches 15.6 °C, about 60 °F. At a normal indoor temperature that puts room air near 72% relative humidity and the cooler surfaces in a house well past 80%, which is where common indoor molds begin to grow. Counting these days is how regional humidity is compared between places.
MoldRiskIQ scorealso: Mold IQ score, Mold IQ: This product's implementation of a mold risk score: a 0–100 number for a single address, composed from four weighted modules — Regional Moisture Burden, Terrain and Drainage, Building Vulnerability, and Disclosure and Event History. Where a generic mold risk score is a category, the MoldRiskIQ score is one specific model with published weights.
Occupant Observations: A scoring module worth up to 20 points, added when the people who live in a building answer a structured intake about what they can see, smell and have repaired. It is the only input that comes from inside the house.
Regional Moisture Burden: The scoring module covering the climate a building has to cope with: average humidity, annual rainfall, flood exposure and storm exposure. Worth 20 points of the model. It describes the region, so every property in a postal code starts from the same regional figure.
score bandalso: risk band: The plain-language label attached to a score: Low below 20, Guarded from 20 to 39, Elevated from 40 to 59, High from 60 to 79, and Severe at 80 and above. Bands exist because a two-point difference between scores rarely means anything, while a band change usually does.
Terrain and Drainage: The scoring module covering where a building sits on its land: elevation relative to its surroundings, slope, and how readily water leaves the site. Worth 10 points. This is the part of the assessment that most often explains why one house on a street is wet and its neighbour is not.
verified year built: A construction year taken from a parcel or property record, or supplied by the owner, as opposed to one estimated from a census-tract median or a community-mapped building footprint. The distinction is carried through the report, because a neighbourhood median presented as a fact about your house is a confident way to be wrong.

Moisture and building science

air leakalso: air leakage, air infiltration: Uncontrolled air movement through gaps in the envelope. It matters for moisture because moving air carries far more water vapour into an assembly than diffusion ever does — a small gap can deposit more water in a wall over a winter than a vapor barrier could ever hold back.
capillary actionalso: capillary rise, wicking: Water moving through the pores of a material against gravity, the way it climbs a paper towel. It is how ground moisture reaches a foundation wall and then the framing above it, without any leak being involved.
capillary break: A layer that stops capillary action — typically between a footing and a foundation wall, or under a slab. Where one is missing, ground moisture moves continuously into the structure and no amount of interior drying resolves it.
dew point: The temperature at which air becomes saturated and water condenses out of it. Unlike relative humidity it does not change with temperature, which makes it the more useful number when comparing one day, one room or one climate against another.
dew point margin: How far a surface's temperature sits above the dew point of the air touching it. A small margin means condensation is close; a negative one means it is already happening. It is a more useful diagnostic than relative humidity because it is specific to a surface rather than a room.
drainage planealso: water-resistive barrier, WRB: The layer behind cladding that catches water which gets past the surface and routes it back out. Cladding is not waterproof and is not expected to be; whether an exterior wall survives depends almost entirely on whether this layer exists and is drained.
drying potential: How readily an assembly gets rid of water it has taken on, and in which direction. It is half of whether a wall survives getting wet — the other half being how much water arrives — and it is the half most often lost when an old building is retrofitted or air-sealed.
negative gradingalso: negative grade: Ground that slopes towards a building rather than away from it, so surface water is delivered to the foundation. It is among the most consequential and most correctable site defects, and it is invisible in listing photographs.
perched water table: Groundwater held above the true water table by a layer of soil that will not let it drain, common where glacial till or clay subsoils sit under a building. It puts standing water against a foundation after rain in places where the regional water table would suggest none.
psychrometrics: The physics of moist air — the relationships between temperature, humidity, dew point and energy that decide where water in a building ends up. It is the reason drying a building is a calculation rather than a matter of running fans until it feels dry.
relative humidityalso: RH: How much water vapour air holds as a percentage of what it could hold at that temperature. It describes air, not surfaces, and it moves when temperature moves without any water being added or removed — which is why a room at a comfortable 50% can still have a wall growing mold behind a wardrobe.
thermal bridgealso: thermal bridging, cold bridge: A path through an assembly that conducts heat faster than the material around it, typically framing or a steel lintel. The interior surface there runs colder than its surroundings, so it reaches the dew point first — which is why growth often appears in regular stripes matching stud spacing.
vapor barrieralso: vapour barrier, vapor retarder: A material that slows water vapour moving through an assembly. Its usefulness depends entirely on which side of the insulation it sits on for a given climate; installed on the wrong face it traps moisture rather than excluding it, which is a common cause of hidden growth in retrofitted walls.
water activityalso: aw: The availability of water at a surface, on a scale from 0 to 1, and the actual variable that decides whether mold germinates. Common indoor species need roughly 0.80; Stachybotrys needs about 0.90. Room humidity is only a proxy for it, because the cold surfaces in a building are always wetter than the air.

Construction and materials

barrier EIFSalso: synthetic stucco, EIFS: An exterior insulation and finish system installed without a drainage plane behind it, common on 1990s construction. Water that gets past the surface has no route out, so it sits against the sheathing.
below-grade living spacealso: finished basement: Habitable rooms below ground level. The finish is the risk: framing and drywall installed against masonry without a capillary break create a concealed cavity that stays damp, and the finishing is what stops anyone noticing.
Chinese drywallalso: contaminated drywall, corrosive drywall: Imported wallboard used in a narrow window of 2000s construction that off-gasses sulphur compounds, corroding wiring and coils and producing a persistent odour. It is often mistaken for a mold problem because the smell and the timing look the same.
construction eraalso: construction-era, decade base score: The decade a building was built, used as the starting point for Building Vulnerability. Each era carries its own failure modes, and the curve is not linear with age: 1990s stock scores worse than pre-war stock, because tightened envelopes without matched ventilation trap water that a leakier old building would have dried out.
crawl space encapsulation: Sealing a crawl space with a continuous liner and bringing it inside the building's conditioned envelope, rather than venting it to outside air. Done well it removes a major moisture source; done without addressing bulk water or providing air movement it seals the problem in.
drainable EIFSalso: drained EIFS, water-managed EIFS: The later form of the same system, with a drainage plane and a drained cavity behind the insulation so water that gets in leaves again. The material looks identical from outside, which is why the installation date matters more than the finish.
hardboard sidingalso: composite siding, pressed-wood siding: Cladding pressed from wood fibre and resin, widely installed in the 1980s and 1990s. Where the factory coating is breached — at cut ends, nail heads and the bottom course — it absorbs water and swells, and the damage runs behind the visible face.
PEX: Cross-linked polyethylene supply piping, the modern flexible plastic standard. It shares polybutylene's appearance-of-plastic and almost none of its failure history; the two get conflated in inspection reports and property listings, and they are not the same risk.
polybutylenealso: poly pipe, PB pipe: A grey plastic supply piping used widely between the late 1970s and mid 1990s, prone to failing from the inside without warning. Its significance to mold is that failures release water inside wall cavities rather than where anyone can see them.

Testing and assessment

air sampling: Drawing a measured volume of air through a collection medium and having a laboratory identify and count what it caught. It reports what was airborne at that spot during those minutes, which is why an indoor result is only interpretable against an outdoor control taken the same day.
clearance testingalso: post-remediation verification, post-remediation testing: Assessment carried out after remediation to confirm the work met its scope. It should be performed by someone with no involvement in the removal, because a firm verifying its own work is answering a question it is paid to answer one way.
containment: Sealing a work area and holding it under negative pressure so material disturbed during removal does not travel through the rest of the building. Its absence is the usual reason a small remediation turns into a whole-house problem.
ERMI: The Environmental Relative Moldiness Index, a DNA-based analysis of settled dust developed by the US EPA as a research tool. It was not validated as a diagnostic for individual buildings, and the EPA has said so; results are frequently marketed as though it were.
moisture meter: A handheld instrument reading moisture content in a material, either with pins driven into it or by non-invasive scanning. Readings are only meaningful compared against a dry area of the same material — which is what separates an old stain from something still wet.
outdoor controlalso: outdoor baseline: An air sample taken outside the building on the same day, used as the comparison for indoor results. Without one, an indoor spore count is a number with no scale — outdoor levels vary by orders of magnitude with season and weather.
remediation: Removing contaminated material, correcting the moisture source, and drying the structure. Removal without correcting the source is cleaning, not remediation, and the growth returns.
scope of work: The written specification of what will be removed, how far past visible damage, how the area will be contained, and what the moisture source correction is. It is the document that makes two remediation quotes comparable, and the one most often missing.
spore trap: The most common air-sampling cassette: air is drawn across an adhesive slide and a laboratory counts what stuck. It captures spores whether alive or dead, which is useful after remediation and a limitation if you want to know what is actively growing.
surface samplingalso: tape lift, swab sample: Lifting material directly off a surface with tape or a swab for laboratory identification. It answers what is growing on that spot, definitively, and says nothing about how much of it is in the air or how far it extends.
thermal imagingalso: infrared camera, thermal camera: A camera showing temperature differences across surfaces. It does not see mold and does not see water; it shows cool patches that often mean wet material behind a finish, which then has to be confirmed with a meter.

Property transactions

caveat emptor: "Let the buyer beware" — the rule in the minority of states with no general statutory disclosure duty, where a seller must not actively conceal a defect but need not volunteer one. It is why disclosure norms have to be checked by state rather than assumed.
general home inspectionalso: home inspection: A survey-level examination of a whole property's condition, covering visible and accessible components. Most inspectors exclude mold assessment in their own scope language — the report will flag visible moisture and staining, and is not an assessment of what is behind a finished surface.
independence: Whether the party assessing a problem stands to be paid for fixing it. It is a hard gate for clearance work and a thing worth knowing about any inspection: the finding may be perfectly competent and the incentive still points one way.
inspection contingency: The clause in a purchase agreement giving a buyer a defined window to have the property examined and to renegotiate or withdraw on what is found. Everything a buyer can discover cheaply happens inside it, which is why its length is worth negotiating before its content matters.
material defect: A problem significant enough that it would affect a reasonable buyer's decision or the property's value. It is the threshold most disclosure statutes turn on, and the reason a seller's honest "no" and an inspector's finding can both be accurate.
seller disclosurealso: disclosure statement, property disclosure: A statement a seller completes about known defects and past problems with a property. Requirements are set by state, not nationally: Pennsylvania, New Jersey and Delaware each use their own statutory form. It records what the seller knows and admits, which is not the same as what is true of the building.

Mold itself

Aspergillus: A very common genus found in most indoor environments, growing at water activity as low as about 0.80. Its tolerance for relatively dry conditions is why it appears in buildings with no leak at all, on surfaces that simply run cold.
hyphae: The branching filaments a mold colony is actually made of. They penetrate the material rather than sitting on it, which is why surface cleaning of porous material removes the visible growth and not the organism.
moldalso: mould: A group of fungi that grow as multicellular filaments and reproduce by spores. Spores are present in every building and cannot be excluded; what varies, and what can be managed, is whether they find sustained moisture on a surface they can eat.
MVOCalso: microbial volatile organic compound, musty odour, musty odor: The volatile compounds a growing colony gives off — the source of the musty smell. The smell is a genuine detection signal, and often the only one available for growth that is entirely concealed.
mycotoxinalso: mycotoxins: A toxic compound some molds produce under some conditions. Production is not constant and not universal to a species, so the presence of a species that can produce mycotoxins is not evidence that any were produced.
Penicillium: Another near-ubiquitous indoor genus with low moisture requirements, typically blue-green. Together with Aspergillus it accounts for most of what laboratories report from ordinary buildings, and the two are often counted as a single category because their spores are hard to tell apart.
sporealso: spores: The reproductive unit mold spreads by, small enough to stay airborne for long periods and present in outdoor air everywhere. A count on its own is not a verdict, which is why an indoor sample means little without an outdoor control.
Stachybotrysalso: black mold, Stachybotrys chartarum: A dark green-black mold requiring sustained wetting — water activity around 0.90 — so it indicates a persistent water source rather than incidental humidity. Many unrelated molds are also dark, and colour is not identification.

Side by side

Terms people mix up

Pairs that get used interchangeably and mean different things.