soil vent

soil vent

[′sȯil ‚vent] (engineering) stack vent

stack vent

stack vent, 1 1. The extension (to the open air) of a soil or waste stack above the highest horizontal branch drain or fixture branch connected to the stack. Also called a soil vent or waste vent.2. In built-up roofing systems, a vertical outlet permitting water vapor, which is entrapped within the insulation, to escape.