drain
quote; No because those are only allowed on island sinks.
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NOT TRUE, because it can also be used when the sink is on a wall which has windows above it and posts at either end, precluding ANY common vent configuration, OR in a knee wall which is not an island. BUT in this case it would be a Draconian situation requiring extensive remodeling. The proper solution is to cut out that kludge and install a proper drain configuration, even if it requires a properly installed AAV, and "properly installed" is the key phrase.