d7e42f72_ES__INC____Roofing_Terminology__VALLEY
(1) An opening designed to convey air, heat, water vapor or other gas from inside a building or a building component to the atmosphere, thereby relieving vapor pressure; (2) Any outlet for air that protrudes through the roof deck such as a pipe or stack; (3) Any device installed on the roof, gable or soffit for the purpose of ventilating the underside of the deck. [VALLEY] 
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ARMKO INDUSTRIES, INC. - Roofing Terminology
VALLEY