Issue link: https://hi.iaq.net/i/248503
www.epa.gov/iaq/moisture Term Definition Cricket A chimney flashing on the uphill side, resembling a small roof ridge, to divert rainwater around the chimney. Drainage or drain plane Any element exposed to weather or otherwise residing at the line between the "wet" and "dry" zones of an exterior wall system or assembly. Dry well A deep hole, covered and usually lined or filled with rocks, that holds drainage water until it soaks into the ground. Eave The protective overhang at the lower edge of a sloped roof. Enthalpy A measure of the total energy of a thermodynamic system. It includes the internal energy, which is the energy required to create a system, and the amount of energy required to make room for it by displacing its environment and establishing its volume and pressure. EPDM Ethylene propylene diene monomer, a synthetic rubber sheet used in single-ply roof membranes. Expansion joint A deliberate separation of two roof areas to allow expansion and contraction movements of the two parts. Fascia The finish covering the edge of eaves of a flat or sloping roof or roof overhang. Fishmouth An opening of the lapped edge of applied felt in built-up roofing due to adhesion failure. Flashing Connecting devices that seal membrane joints, drains, gravel stops and other places where membrane is interrupted. Base flashing forms the upturned edges of the watertight membrane. Cap or counter flashing shields the exposed edges and joints of the base flashing. Forebay A small pool located near the inlet of a storm basin or other storm water management facility. These devices are designed as initial storage areas to trap and settle out sediment and heavy pollutants before they reach the main basin. Gravel stop A flanged device, normally metallic, designed to prevent loose aggregate from washing off the roof. It also provides the finished edge detail for built-up roofing assemblies. HVAC Heating, ventilation and air conditioning. Hygrothermal Pertaining to heat and humidity. Impervious Not letting water or moisture pass through or be absorbed. Micromanometer An instrument designed to measure minute differences in pressure. Modified bitumen Asphalt with the addition of polymer modifiers to increase cold temperature flexibility and warm temperature flow resistance and stability. OSB Oriented Strand Board. A type of particle panel product composed of strand-type flakes that are purposefully aligned in directions that make a panel stronger, stiffer and with improved dimensional properties in the alignment directions than a panel with random flake orientation. Parapet The part of the wall assembly above the roof. Plenum Space between a suspended ceiling and the floor above that may have mechanical and electrical equipment in it and that is used as part of the air distribution system. The space is usually designed to be under negative pressure. Ponding The collection of water in shallow pools on a roof surface. H-2