This glossary is grouped into two parts: terms about moisture and the building, and terms about odor and how professionals deal with it. Each definition is short and practical, with a note on why it matters for a musty smell. If a provider uses a term that is not here and will not explain it plainly, that is worth noticing.

Moisture and building terms

Relative humidity (RH)
How much moisture the air holds compared with the most it could hold at that temperature. Cool basement air reaches high RH quickly.
Dew point
The temperature at which moisture in air condenses. When a wall or pipe is below the dew point, it gets wet.
Stack effect
Warm air rising and leaving the top of a house, pulling air in from below, including from basements and crawl spaces.
Efflorescence
White, chalky mineral deposits left on concrete or brick when water passes through and evaporates. A sign that moisture moves through the wall.
Vapor retarder
A material that slows water vapor, such as polyethylene sheeting on crawl space soil.
Encapsulation
Sealing a crawl space with a heavy liner on the ground and walls, closing vents, and controlling humidity inside.
Window well
The enclosure that holds soil back from a below-grade basement window. Needs drainage at the bottom.
Grade
The slope of the ground around the house. Positive grade slopes away from the foundation.
Sump pit
A pit in the basement floor that collects water from drain tile, often with a pump. Also a common radon and odor entry point if unsealed.
Lateral
The sewer pipe from the house to the public main. Usually the owner's responsibility.

Odor and treatment terms

Musty odor
A stale, earthy smell commonly produced by mold and mildew growing on damp materials.
Trap seal
The water held in a drain's U-bend that blocks sewer gas. It evaporates if the drain is unused.
Masking
Covering an odor with fragrance without removing its cause.
Source removal
Taking out the material that produces or holds the odor, such as wet pad or moldy drywall.
Encapsulant or sealer
A coating applied to cleaned, dry surfaces to lock in residual odor. Not a substitute for removing growth.
Oxidizer
A chemical or device, such as ozone or hydroxyl generators, that breaks down odor molecules. Some require the space to be vacated.
Remediation
The removal of mold growth and contaminated materials under controlled conditions, usually followed by cleaning and drying.
Containment
Plastic sheeting and air controls used during remediation to keep spores and dust from spreading to the rest of the house.

General information for Lakewood, not a quote or professional advice. In an emergency, call 911.