Does a fixture connected directly to the ground stack (vented) need to be vented separately?
Generally speaking: A Stack (even if it's vented) is not a Vent if it has a toilet on it above the point you want to use it as a vent. Older installs may not respect this. There were problems with not respecting this, code changed to solve them.
You can run a (dry) vent up to a point &quot;6 inches (or more) above the flood rim of the highest fixture on the floor served&quot; and join to the Stack where it IS a vent. In that case it would be the highest floor served, but you can join vents for the basement 6 inches above the flood rim of the highest fixture in the basement - but you can't then join that to a stack with a toilet above. You can run it parallel to the stack until you are 6&quot; above the highest fixture and then join the stack.