Above-Grade Waterproofing – The prevention of water intrusion into the exposed parts of the dwelling above ground level through the use of materials or systems that are not exposed to hydrostatic pressure.
Absolute Humidity – The amount of water vapor present in a unit volume of air.
Absorption – The accumulation of water or vapor drawn directly into the structure’s cells.
Adobe – A brick or building material made of sun-dried earth and straw
Aqueduct – A conduit for carrying a large volume of flowing water.
Backfill – To fill an open excavation with excavated material.
Backhoe – An excavation machine with a large bucket used for digging and back-filling around the exterior of the foundation in certain types of waterproofing processes.
Basement – One or more floors of a structure that are partially or fully below ground level.
Basement Waterproofing – The control of water to prevent flooding of basement floors.
Bedrock – The solid rock layer under the surface of the soil.
Below Grade – Any part of the house or structure that is underground or beneath ground level.
Capillary Action – The wick-like migration of water into the porous walls and floor in the same manner as water is drawn into a sponge.
Check Valve – A device that permits water flow in only one direction and is commonly installed in the sump pump discharge line.
Condensation – The conversion of a molecule of moisture/vapor that when exposed to something colder, decreases in size and squeezes out the denser liquid. This occurs on the cooler walls and floors and pipes in basements much the same as it does on the outside of a glass of ice water, and is always worse when the relative humidity is highest. (See “Dampness” for remedies)
Cove/Wall Cove – The joint where the wall and the floor meet. This is a common area for water intrusion in a basement.
Cracked Walls or Floors – Cracks can form in walls and floors for a number of reasons from settlement, expansion and contraction, water pressure and even by design. The crack is not the problem it is only the symptom. Water entering through the crack is a problem and only enters when there is enough pressure to force it to penetrate the opening. Eliminate the pressure and eliminate the water.
Crawl Space – A shallow unfinished space beneath the first floor or under the roof usually for access to plumbing, heating ducts and wiring. Crawl spaces should have adequate ventilation to reduce the effects of condensation and to expel stagnant air.  Water pipes should be wrapped especially in unheated spaces.
Dampness – Liquid diffused or condensed in a relatively small quantity on the walls or floor. The effects of moisture created from capillary action or condensation and can often be controlled by heating the space, having adequate ventilation, by using a properly sized dehumidifier or a combination of all the afore mentioned remedies.
Dampproofing – An application or system that is installed when the house is built to resist water vapor or minor amounts of moisture and acts as a backup to primary waterproofing systems. Dampproofing materials are subject to the effects of weathering and deterioration and are not effective against water pressure.
Dehumidifier – An appliance that condenses air molecules using cold temperatures which in turn “squeezes” the moisture out of the molecule into a tray which must be emptied when full. It is best to have the unit sized for your particular needs by a qualified representative at the local hardware or building supply store as an under-sized unit is of little value.
Discharge Line – The pipe used to direct the water away often from a sump pump. Discharge lines should be checked periodically to insure there are no obstructions that might restrict the water flow. Long discharge lines will freeze under the right conditions and should be kept as short as possible in northern climates.
Down Spout – The pipe from the roof gutter system that, in conjunction with the leaders, directs the roof water away from the foundation.
Drain Tile – Previously made of clay and other hard materials laid end-to-end, drain tile is now commonly made of flexible, perforated polyethylene tubing and is laid near the footing level to aid in the control of below grade water problems.
Efflorescence – The staining and discoloring of masonry walls and floors as a result of water-carried acids and chemicals. Often confused with mildew in appearance.
Epoxy Injection – The injection of low-viscosity epoxy materials into foundation cracks of the wall. However, if continued movement or settlement occurs the epoxy will crack.
Footing – Concrete poured into a form below the frost line and above the normal water table and allowed to cure. This then becomes the base upon which the walls are built and helps to distribute the load.
Freeze-Thaw Cycle – The cycle of water freezing and later thawing and the effects it has on the material it is around or absorbed into often is a contributing factor to basement water problems.
French Drain – The moving of surface water away from an area.
Gap or Floating Floor – The space left in the cement, usually by the wall, to accept water from above floor level directly into the drainage system and also to allow for expansion and contraction of the floor.
Hollow Block Foundation – Block walls that have open hollow cavities designed within the block. These cavities allow water to collect inside the walls and cause a myriad of problems.
Humidity – A moderate degree of wetness especially of the atmosphere. High relative humidity can result in wetness condensing on basement walls and floors, just as it does on other cooler things such as water pipes. The use of a dehumidifier and/or adequate ventilation is recommended to reduce or eliminate the effects of condensation.
Hydraulic Cement – Sometime referred to as “Hot Patch” because of the heat generated during its exceptionally quick curing time. Often used to patch cracks and small areas that have minor water seepage. May come loose during movement or settlement.
Hydrophilic – Chemical properties that draw or absorb water.
Hydro Static Pressure – “Still Water” pressure. Often caused by a high water table it is the pressure exerted against the foundation by various heights of water at rest. The same type of pressure you feel when you try to push a bucket into a pool of water. To some degree, this is the same pressure that allows gigantic ocean liners to stay afloat but this pressure has an adverse effect on the integrity of the foundation of a building.
Infiltration – The inadvertent leakage of water, moisture, vapor or air into the building.
Iron Bacteria (The “Orange Stuff”) – An orange colored slimy substance, often mistaken for clay residue, that can clog drainage systems and sump pumps. It is actually a bacterium that feeds on the nutrients (iron ocher) of the flowing water. Chemical formulas, such as “Iron Out” will release the bacteria but be sure to follow label instructions. Another way to release the bacteria is by flushing the system with hot (140 degree) water.
Membrane – A flexible elastomeric material applied to the exterior of the building.
Moisture – See “Dampness”
Monolithic Floor – When the floor and footing are poured together and become one single unit. The walls are then built on top of the floor. This is usually evident in a block foundation when the first block is a whole block with a mortar line under it on top of the floor.
Poured Concrete Foundations – Walls made by pouring concrete into forms, usually held together by tie-rods. When the forms are removed the tie-rods are clipped and this location often leaks because of thermal movement, the curing process and when water pressure is present.
Pressure Relief System – Below grade drainage designed and installed to reduce the effects of hydrostatic pressure at a level below the basement floor.
Sealant – A material applied to exterior building joints. Sealants should be capable of withstanding continuous joint movement during all weather conditions without failing.
Shelf Life – The maximum time that packaged and unopened waterproofing materials can remain usable.
Solid Block Foundation – Block walls that are completely filled with cinder of concrete and have no hollow cavities and usually leak at the mortar joints.
Spall/Spalling – The crumbling or breaking off in small pieces of concrete or masonry usually as a result of the freeze-thaw cycle or deterioration (rusting) of reinforcing steel or tie-rods.
Stone Foundation – Walls made of large stones stacked on top of one another and usually held together with a mortar type substance. This type of foundation is usually older and when the mortar deteriorates it allows more water to pass between the stones and not only cause water damage but structural damage as well. Because the stones are not all the same size and shape, the interior side of the wall is semi-smooth but the exterior side is not, which causes complications when trying to waterproof from the outside.
Sump Pit – A hole dug to a depth that would accommodate a sump pump and serve as a collection receptacle for water. A sump well liner or crock is usually placed in the pit to keep the walls of the hole from collapsing and should have a bottom on them so dirt doesn’t get pumped out with the water and undermine the foundation.
Sump Pump – A pump designed to work in and under water to remove accumulations of liquid from a sump pit.
Tensile Strength – The ability of a waterproofing material to resist being pulled or stretched apart to a point of failure.
Thermal Movement – Movement, either expansion or contraction, caused by temperature changes.
Tie-Rods – A rod  (steel) used as a connecting member or brace to hold forms in place when pouring concrete walls that are clipped when removing the forms.
Water Penetration/Infiltration – The condition where water enters the interior areas of a structure.
Water Table – The upper limit of the portion of the ground totally saturated with water. This is a major cause of below grade leakage especially through the floor, cove and lower part of the walls of the basement.
Weep Holes – Holes generally drilled in the lower course of hollow block walls near the footing that allow water trapped inside the cavities to escape.