Final answer:
A gas vent must extend through the roof or exterior wall and terminate outdoors with a vent cap or similar device to safely dispel exhaust gases from appliances.
Step-by-step explanation:
A gas vent must extend through the roof or an exterior wall and terminate outdoors with a vent cap or similar device. The purpose of the gas vent is to dispel exhaust gases from appliances like water heaters or furnaces safely to the outside atmosphere, preventing them from entering occupied spaces where they could pose health risks.
It is important that the vent extends to a sufficient height or distance from windows and other building openings to avoid the backdraft of gases into the building. Local building codes typically specify the required height and termination details to ensure safe ventilation.