Glossary of Terms for Home and Building Water / Moisture Problems, Solutions and Prevention

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Air-entrained—Concrete that has been combined with chemical additives. The additives make the concrete more dense and resistant to moisture penetration, and also reduce damage to the concrete from freezing temperatures.

Argon gas—Gas that has a higher R-value than air. Argon gas is injected between two panes of glass to decrease heat loss through window units.

Asphalt coating—Coating that's applied to the exterior surfaces of concrete basement walls to seal them against moisture penetration.


Chimney effect—Reference to the fact that hot air rises. Cool air entering the attic from soffit vents rises and rises as it warms in the attic, then exits through high-level or ridge vents.

Circuit breaker—Electrical device that's used to replace the old fuse system in electrical wiring. When a fault occurs in the electrical system the circuit breaker switches off to stop current flow through the circuit.

Condensation—Occurs when moisture-laden air meets a cold surface and condenses to become water.

Cornice—A board which finishes off the roof overhang on a gable roof.

Cove—Concrete troweled to form a 45-degree angle at the joint where the concrete basement wall meets the footing below. The cove is designed to shed water away from the joint.

Curtain drain—A drainage trench to disperse water. A drain pipe is placed at the bottom of the trench, then gravel is poured into the trench, up to a level several inches below the ground level. Then black dirt is added and sod is laid so the drainage ditch is concealed.

Cricket—A pyramid—shaped metal device that's installed behind the chimney on the high side of the roof slope. The cricket diverts roof water around the chimney and prevents water from pooling at the joint where the roof and chimney meet.


Double-hung—Term that describes a style of window in which the upper and lower units can be opened and closed by moving the units up or down in their channels.

Downspout—The rain gutter member that carries water from the horizontal rain gutter to the ground.

Drain pipe—Perforated plastic pipe that's buried in the ground at footing level, or in the bottom of a drainage ditch to catch and divert water away from the foundation or drainage ditch.

Dry rot—Term that describes rot or deterioration of wood members due to water exposure.


Elbow—A device used to change the direction of flow on a rain gutter system.


Fascia—Horizontal wood trim used to finish and enclose the ends of the rafter tails at the roof overhang or soffits.

Filter fabric—Fiberglass fabric or mesh that's used to cover underground drain pipes. The fabric permits water to flow through, but stops soil from washing down and plugging the perforations in the drain pipe.

Footings—The concrete slab that supports the weight of the foundation or basement walls. The foundation must always rest on undisturbed soil to prevent settling that occurs in loose-fill soil.


Grade—The slope of land is called the grade.

Ground pipe—The horizontal rain gutter member that carries water from the bottom of the downspout to a point away from the foundation.


Heat exchanger—An appliance through which runs an exhaust pipe and a fresh air intake pipe. As the warm stale air passes out, heat is transferred to the incoming cold fresh air. The device thus permits fresh air to be exchanged for stale air in the house, while retaining the desired heat.


Mildew, mold—Fungi which thrive in conditions where heat, moisture and decay exist. Mildew spores can be killed by chlorine bleach; wash away with water and detergent.


Oxalic acid—Acid that's available in crystal form at most paint centers. Oxalic acid is mixed with water to bleach wood that has been darkened by moisture exposure.


Parge coat—A 50-50 mix of cement and fine sand. The parge coat is troweled over the concrete block foundation wall to provide a barrier to water entry.

Percolation—The rate at which soil absorbs water: the percolation rate varies greatly depending on type of soil, i.e., sandy, loam, clay, etc.

Perm factor—The rate at which moisture can pass through a building member or material.


Rain gutters—Plastic or metal troughs which catch and

transfer water from the roof to a disposal area.

Retaining wall—A wall of brick, stone or wood built to pre vent soil erosion at the point where the grade level changes. The wall must permit water to pass through while retaining the soil in place.

Ridge—the apex or highest point where two roof planes meet. Also, ridge vent, a ventilator which permits stale hot air to be exhausted from the attic while preventing water entry.


Sealer—A paint-like material applied to masonry surfaces to reduce moisture entry through the wall, etc. Skylight—A window that's installed through the roof to permit entry of light and , if operable, air. When improperly installed and flashed the skylight can be a source of roof leaks.

Slope—The rise or fall of a surface such as a roof or the land.

Soil percolation—See Percolation, above.

Splash block—A plastic or concrete device that's placed on the ground below a gutter downspout. The splash block serves a dual purpose: it prevents soil erosion from the water flow while also directing the water away from the foundation.

Strainer—A dome-shaped wire device that's installed in the gutter at the point where the downspout hole occurs. The strainer prevents leaves and roof debris from entering and clogging the downspout.

Sump, sump pump—A catch basin to collect water from soil drain pipes. The collected water is picked up by a sump pump and transferred to a disposal point away from the house structure.

Swale—A shallow ditch or depression in the soil, created to divert water to a new path around and away from the house structure.


Transit—An optical device that's mounted on a tripod. The surveyor peers through the eyepiece at a calibrated surveying stick held by an assistant, to check the lay or slope of the land.


Valley—The juncture at which the roof changes direction or plane. The flashing used to waterproof this juncture is called valley flashing.


Water table—The point in the earth at which the soil is continuously wet. The first step in finding the source of basement water is to check with your building department to learn the depth of the water table.

Whole-house ventilation—This type of ventilation employs a large-capacity fan to exhaust warm, dry air from the house interior into the attic, where it's removed via roof or ridge vents.

Window well—A u-shaped device made of fiberglass or metal, that's placed around a basement window that's below grade. The units permit basement windows to be below the ground level while providing sunlight and fresh air to enter the basement.

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Updated: Tuesday, July 7, 2009 18:42